After the novella that I turned last week’s post into I will change the pace for this week and write about something else I get asked about a lot and that more people can likely relate to than last week’s Tech Talk deep dive into fuel maps and CPP props. And a lot shorter!
Hope you enjoy and let me know in your comments either way.
Green Grass Prototyping
In one of my former lives I was a drafting and CAD teacher and in the architecture classes I taught I showed my students the value of what I referred to as the “Green Grass” approach to prototyping.
I took this title from a practice that I had first run into when I was attending the University of British Columbia in Vancouver and they were doing some major construction projects on this hugely awesome 400 hectares/1000 acres campus. When it came time to put in the many sidewalks and pathways around the campus rather than do the typical set of engineering studies to determine minimum walking distances, foot traffic density and the like, they instead just planted all these areas in grass for the first year. After being used that first year they went back and simply put in sidewalks and walkways on top of all the well trodden pathways had been made by all the people walking on them for the past year. I thought this was a brilliant method that I admired for its humbleness of seeing that the users were the true experts and that “we is smarter than me” type of approach. I have gone on to use this approach for the rest of my life and applied it conceptually to most of my many “build” projects over the past 50 years, the latest of which is the design and building of our new boat Möbius. Hence this week’s title. Seemed all quite apropos that I should come across this perfect example on my walk to the bank yesterday in the small town of Finike Turkey where we are currently docked and working on Möbius at the Setur Finike Marina.
Pretty clear proof that the civil engineers who did this recent renovation miscalculated and forgot to put in this section of walkway that more people than me thought should be there! I find this Green Grass Prototyping to be one of those concepts that is so simple and easy to understand, yet ever so smart and powerful. I thought it was worth writing about both because I get a lot of related questions about some of the ways we have used this on Möbius and I also hope that it is a concept than many of you will find useful and powerful in some of your own projects. Here are a few examples we have right now on Möbius.
Shading & Cooling of Super Salon
After living aboard for over seven months now, we are eXtremely pleased with the 360 degree views we have through the 26mm/1” thick glass that surrounds the SuperSalon or Pilot House. It is a thrilling place to be both day and night. We knew that all this glass would require some additional attention to control the heat coming in from the sun as well as the heat going out at night and we have quite a few options as to how to control both of these. As with most parts of boat design it is all about juggling the various pros and cons of each option and deciding which one will be the just right, just for us, Goldilocks choice. In many cases this is exacerbated by the fact that in order to evaluate many options you need to live with it for awhile and experiment with different arrangements before you will know how each possible solution works and how well it does or does not fit you. For controlling the PH windows we have options that include applying some of the amazing new films that are being made, using blinds on the inside or using shade cloth on the outside. This is where the Green Grass prototyping really shines and so we have been applying it to the shading of the SuperSalon glass. For the past few months we have had this nylon mesh garden shade material draped around the sides and front of the SuperSalon. We bought a 20m length of 2m wide shade cloth that is readily available from home improvement and hardware stores as it is used extensively for everything from shaded overhangs on cafes to semi-privacy screening on link fencing.
And I used some of these plastic spring clamps in my Workshop to clamp the unused width of the cloth to the AL pipe handrails running all around the roof overhang.
This has been working really well as it allows us to lift it up out of the way entirely in a few seconds and so we can experiment with how much of a difference it makes in the morning vs afternoon sun, etc.. One of the unexpected things we’ve learned is that in addition to reducing the amount of UV and sunlight getting through the glass, this draped material keeps the glass itself much cooler and also forms a bit of an air insulation pocket in the large space between the cloth and the window glass. Being loose and not attached at the bottom seems to also help in that there is a natural breeze blowing through this space keeping it from trapping hot air inside. It looks completely blacked out from the outside but when you are inside there is still reasonably good visibility so you know what is going on around you. Still early in our prototyping phase with this but our current thinking is that we will still likely go ahead and put in some film on the outer surfaces that will reduce the UV and heat transfer without adding much tint or colorization. But we think we will also do a more finished installation of this shade cloth by putting in some tracks or fasteners around the top and bottom and sewing up a strip of the shade cloth to attach to these. Right now we are enjoying the HUGE difference this has made to the inside temperatures in the hot up to 40C/105F we’ve had this summer.
Another place where we have been applying the Green Grass approach is with the furniture in the large area up in the SkyBridge. We purposely left his large area open and then Christine found some inexpensive patio furniture that fit just right into the dimensions of this area. It is all loose and easily moved about so we are trying out different configurations of these furniture pieces for a month or so at a time while we enjoy it each breakfast and evening sundowner’s. We pay attention and talk about what we like, what’s working, what’s not with each configuration and I will use these when it comes time to build in a more permanent solution. A good example of where this prototyping really pays off is that I’ve realized that the AL frame running around the circumference of the windows where they transition from fixed tinted glass to removable panes of clear acrylic, ends up being at the same height as our eyes when we are sitting down. This gets in the way as you are looking out and showed us that we will want to install a raised platform for this area where the furniture will sit. This will also make it easy for me to convert the table to a pedestal style that can be raised and lowered and will give us some easy to access storage under the platform. I will build a prototype of this platform as well using PVC pipe and fittings for a framework and some plywood for the raised floor so we can Green Grass the platform as well and figure out the best shape and height.
Media Filter v2.0
I’ve also been doing some Green Grass prototyping with the media or sand filter that does the bulk of the work filtering the sea water being pumped into our Delfin 250L/hr watermaker.
Apparently my first attempt with this plastic tank pool filter wasn’t quite up to the job as the 45PSI feed pump pressure proved too much for the seam and it split. So I found a more robust model that I could get shipped in here which is no easy task let me assure you, and spent 2 days getting this bad boy installed. As you can see it is wrapped in glass fibre to withstand much higher pressures. Unfortunately the only size that would fit moved the six position valve (black plastic bit on top of the white watermaker) from the top to the side so it took me a bit longer to figure out how best to re-route all the hoses and get everything to fit. It was close but I ended up being able to get it to fit just nicely behind the Blue filter body and still allow me to see the various pressure gauges I have on the plumbing and to fit all the hoses coming in and out. The low pressure (45 PSI) Feed Pump first pushes the sea water from the sea chest through the Blue media filter which removes almost all of the algae, dirt, etc. and then it goes through the 25 micron filter on the Right here before going through the final 5 micron filter. All in all it worked out very well. These media filters are not commonly found in marine Watermakers but they really do dramatically reduce the amount of filter cleaning and maintenance. Without one of these I would typically need to clean each of the 5 & 25 micron filters before each use and replace them about once a month. In my previous boat, adding a media filter reduced this to changing these two filters about once a year and even then they were still very clean. Inside the big Blue filter body, I first fill the bottom 10cm/4” (similar to the “Grade 2” in this illustration) with crushed rock about 20mm / 3/4” in size These rocks cover the spokes or laterals in the bottom of the filter and prevent the mesh surfaces from clogging with the sand above. Super simple in operation, no moving parts, the water enters at the top and the water pressure pushes the seawater through the full height of the sand and then exits out the bottom outlet. Rather than typical pool sand, I use what is called Zeolite which is far superior to regular pool filter sand in that it traps MUCH more and much finer particles and it cleans out much easier when back flushed. From what I read Zeolite is a natural mineral formed millions of years ago in volcanic ash flows that settled in seas and lakes. Zeolite a filtration area of about 1,000 times greater than sand media beds and the key to the truly amazing performance of this all natural Zeolite is in its molecular structure which looks like this. Much more surface area to trap finer particles in much higher volume than grains of sand. After each run of the watermaker it takes me about 3 minutes to backflush the media filter with fresh seawater by simply moving the handle on the filter valve to “Backwash” and then about 30 seconds at “Rinse” and it is all clean and ready for the next run.
The mechanical pressure gauges and Maretron pressure sensors make it easy for me to monitor any clogging of any of the filters and know which one is clogged.
I could argue that fresh water is ultimately even more critical than diesel fuel for us in order to live the completely self sufficient and eXtremely remote life style we do, so having these extra layers of filtration and dramatically lowered maintenance tick of all four of our SCEM priorities of Safety Comfort Efficiency and Maintainability.
Self Sufficient Freedom
This is especially relevant when we are at the very tiny remote islands we so enjoy which often have very limited fresh water for themselves. This is one of many favorite such spots we’ve been to, here in the Lau Group of islands in Fiji with a total of about 120 residents ashore when we were there in 2015. In several instances in our past experiences our watermaker proved to be quite the relationship builder wherein we were able to add value to the lives of those ashore by providing them with more fresh water rather than showing up wanting to take it from them to fill up depleted fresh water tanks onboard. This is the Aur atoll in the Marshall Islands when I was there in 2012.
Having a watermaker is also a key factor in our #1 benefit of this lifestyle which is Freedom. Without a watermaker, passage making boats often have their schedules dictated by the range of the supplies they carry. This applies to electricity needing to recharge batteries with shore power, diesel fuel when your tanks are too small to allow greater range and to fresh water as I’ve outlined above.
Being able to make all the electricity and water we need and having enough fuel that we only need to fill up about every 18 months allows us to travel the world with an eXtremely clean and minimal wake of disruption of the world around us.
It means that when we reach our next destination we have no demands often constrained shoreside resources and no stress from desperately seeking more water, fuel or electrical power.
Thanks for joining me again this week, hope it was enjoyable and you learned something. Please add your comments, what you learned, what you are still curious about, in the “Join the Discussion” box below.
In the post two weeks ago, I posed the question in the title “What Moves a Boat?” and went on to fill in the blanks around the answer which is the propeller because the engine “just” spins the propeller. In that post I went on to outline the relationship between the different types of Horse Power or HP measurements such as theoretical maximum power, power in the propeller shaft and most importantly power that is absorbed by the propeller. A lot of this has a very direct bearing on one of the key metrics most of us keep track of and that is the fuel burn rate or how much fuel does it take to go a set distance on a given amount of diesel fuel. However I spent so much time going through the power and engine side of the equation that I didn’t get to the propeller part itself. So consider this Part II of the “What Moves a Boat?” question.
Since that post and throughout the build actually, I received quite a few questions along the lines of “OK, but what about the propeller then?” and “Why did you chose to use a CPP Controllable Pitch Propeller on Möbius?” so I will do my best to answer these and other questions I’ve received in today’s posting.
Those of you who don’t find these technical discussions to be your cup of tea, probably most of you, please feel free to take a break from your devoted reading of these Möbius World blogs and I’ll try to have something different for next week’s update. And I will issue a warning right up front here that reading the article below may well bring back memories of your high school math and physics courses. I’ll let you decide if that is a good thing or bad?!
It may also help you to know that I named my previous boat sv Learnativity for a very good reason and she definitely lived up to her name in the 15 years I spent sailing her around the world. For Christine and I, two former teachers as well, Learning and Loving are the keys to living life well and that is what we aspire to do every day. Might help you understand what drives us to do things like designing and building Möbius and then writing articles like this one and others here on the Möbius.World blog so we can share all of our lessons learned with you.
Horses for Courses:
I promise to get to propellers as quickly as possible but it is neccessary to understand a wee bit more about the engine power that turns every propeller. It is not widely understood that for most diesel engine models from most manufacturers, the same engine model can be configured for several different service ratings, each with their own different set of HP, torque and fuel burn ratings. This is done so that the same engine can be set up to match the use case of the vehicle or boat that it is installed in. I am oversimplifying it but in marine applications these different configurations typically go from Continuous for engines needing to run at full load aka WOT or Wide Open Throttle 24/7 for days and weeks at a time, up through a series of other models as the use rating goes down to where the engine is only needing to produce peak output for a few hours a day. As you might guess as you go “up” this range, the Horse Power and the RPM goes up with each step as does the fuel consumption. It should also be noted that these same engines also start acquiring some “add on” equipment such as turbochargers, after and inter coolers, etc. but the base engine, block, crank, pistons, etc. are the same.
For example, below is a well done explanation by John Deere for their “M rating” system for their marine diesel engines. (click HERE for link to full PDV version) Keep in mind that these M ratings apply to the same overall engine model, let’s say their JD 4 cylinder 4045 4.5 liter engines or their JD 6 cylinder 6068 6.8 Liter model.
M1 rating is for marine propulsion applications that may operate up to 24 hours per day at uninterrupted full power. These applications typically operate more than 3,000 hours per year and have load factors* over 65 percent. Possible applications: Line haul tugs and towboats, fish and shrimp trawlers/draggers, and displacement hull fishing boats over 18 m (60 ft).
M2: The M2 rating is for marine propulsion applications that operate up to 3,000 hours per year and have load factors* up to 65 percent. This rating is for applications that are in continuous use, and use full power for no more than 16 hours out of each 24 hours of operation. The remaining time of operation must be at cruising † speeds. Possible applications: Short-range tugs and towboats, long-range ferryboats, large passenger vessels, and offshore displacement hull fishing boats under 18 m (60 ft). Marine auxiliary power engines for dedicated hydraulic pump drives, dredge pumps, or other constant-load marine applications should use the M2 rating.
M3: The M3 rating is for marine propulsion applications that operate up to 2,000 hours per year and have load factors* up to 50 percent. This rating is for applications that use full power for no more than four hours out of each 12 hours of operation. The remaining time of operation must be at cruising† speeds. Possible applications: Coastal fishing boats, offshore crew boats, research boats, short-range ferryboats, and dinner cruise boats.
M4: The M4 rating is for marine propulsion applications that operate up to 800 hours per year and have load factors* below 40 percent. This rating is for applications that use full power for no more than one hour out of each 12 hours of operation. The remaining time of operation must be at cruising† speeds. Possible applications: Inshore crew boats, charter fishing boats, pilot boats, dive boats, and planing hull commercial fishing boats.
M5: The M5 rating is for marine recreational propulsion applications that operate 300 hours or less per year and have load factors* below 35 percent. This rating is for applications that use full power for no more than 30 minutes out of each eight hours and cruising† speed the remainder of the eight hours, and do not operate for the remaining 16 hours of the day. Possible applications: Recreational boats in the U.S., tactical military vessels, and rescue boats outside the U.S.
Probably easiest to understand in table format like this. Putting this all together, here is the table of the eight different models of the JD4045 four cylinder marine engines John Deere offers. As you can see the HP ratings range from 75HP @ 2400 RPM for the M1 version all the way up to 150HP @ 2600RPM for the M4 model.
Mr. Gee’s Power Curves:
Just before I finally jump into discussing our CPP propeller on Möbius, let me quickly summarize the power curves from Mr. Gee himself, our Gardner 6LXB six cylinder diesel engine that is fully NA or Naturally Aspirated with all mechanical fuel injection, no turbo, no inter/after cooler.
All 6LXB’s can be setup for several different configurations along the lines of the M ratings of the John Deere outlined above and in our case for Mr. Gee and our XPM hull and use cases, we have set it up for a 100% Continuous Duty able to produce 150HP @ 1650 RPM.
Thanks to Michael Harrison and the other great people at Gardner Marine Diesel in Canterbury England I was able to get this copy of an original graph of all the outputs of the Continuous 100% Duty Cycle version of the 6LXB taken directly while running on their dynamometer.
I took the best photo I could of this very old paper chart so you may want to click to enlarge to read it better.
As per this graph, there are 5 numbered curves mapped out:
Max. power available from engine
Max Shaft Power
Power required by typical propeller
Fuel consumption max power absorbed
Fuel consumption prop power absorbed. If it helps, I have done my best to extract the following data from these curves and put them into this brief chart:
As we now get into our discussion about CPP propellers (finally!), curve #3 is the most relative as this is the power that a “typical” fixed propeller can absorb at these different RPM so that’s the curve to keep in mind here.
Fixed vs Controllable Propellers
Fixed props FP are pretty straightforward and common so I don’t think I need to go into these in much detail. Their basic dimensions are outside diameter, pitch, # of blades, etc. Pitch refers to the angle of the blades and as this angle increases the propeller “bites” into the water more. You order a fixed propeller after carefully working with the manufacturer and providing them with the data about your boat such as hull type, displacement, engine power curves, cruising speed, etc. and they calculate the prop diameter and pitch and manufacture the propeller to match.
Tying this all together, a correctly pitched prop is one that allows the engine to achieve a few more RPM’s above its rated WOT or Wide Open Throttle. This is done to ensure that you can not overload the engine and damage it and most manufacturers will void the warranty if the boat has been “over propped”.
All very logical and reasonable until you start to look at it more closely or more likely you actually get out there and run a boat for awhile and see what the real world performance and fuel consumption numbers turn out to be.
What you end up discovering are two fundamental limitations of a fixed prop:
A FP is pitched to be just right at one RPM, one HP output and one set of conditions or load. In all other conditions the pitch is less and less optimal. In this one scenario the fixed prop can be more efficient because it has been designed to be able to absorb all the power the engine can produce. However, at any other RPM or set of conditions and load a fixed prop is either over pitched or under pitched, running less efficiently and consuming more fuel.
Most of the time in most conditions you need much less power and torque than the maximum power available and so you run the boat with much lower loads which usually reduces the lifespan of that engine. This is exacerbated by the trend for the past decade or more for boat manufacturers, under pressure from buyers, to put in more and more HP rated engines and so it is quite common for boats to spend most of their time running at 10 to 20% of their full load rating which sets them up for very nasty results such as glazing cylinder walls, running too cold, etc.
Engine manufacturers recommend ways to try to reduce the consequences of running their engines in these low load conditions such as running them at WOT for a percentage of the time you have been running them at low loads, but you can see how this is far from desirable and a very poor fit for an eXtreme eXploration Passage Maker XPM type of boat and use case.
In summary then, with a FP boat, in many situations you end up running the engine inefficiently, using more fuel and reducing the lifespan of the engine. I don’t want to overstate this too much and there are of course thousands if not millions of boats running with fixed props so please don’t misconstrue my overview above to be saying that fixed props do not work. They absolutely do and can work quite well.
But as I repeat ad nauseum perhaps, we have our four fundamental SCEM principles for Möbius and all XPM type boats Safety, Comfort, Efficiency, Maintenance and so we are always looking to maximize all four of these and IF there is a better overall solution that helps us optimize one or more of these SCEM principles without compromising the others, then that is usually the Goldilocks choice we make. In the case of FP vs CPP, it became clear to us that CPP helped us make gains in all four of the SCEM categories, and especially so for Efficiency.
The CPP Efficiency Factor
I am going to resist the temptation, lucky you, of writing my own version of a deep dive into how and why a CPP prop enables you to achieve otherwise unavailable efficiency of both fuel consumption and engine maintenance and life span. Instead I will off load that explanation to the following two very well written articles on CPP propulsion.
** There is also a thread on the Trawler Forum with a discussion about the pros and cons of FP vs CPP HERE
The first is THIS one “Controllable Pitch Propellers” by the Naval Architect Michael Kasten’s at Kasten Marine Design. It was written back in 2001 but nothing has changed in this regard since and Michael does a very good job of walking your through the benefits of a CPP propelled boat. I will reference this article again a bit later as he also does an excellent comparison of the costs of building a new boat with FP vs CPP.
The other very worthwhile read is THIS eXcellent posting on CPP props by Matt Marsh. Matt published this very well written article back in April 2013 as part of a much larger “book” of which this is one chapter. All this is over on the eXcellent Attainable Adventures blog that John Harries has eXpertly curated over many years. If you are unfamiliar with this blog I can highly recommend that you spend a few minutes checking it out and I think many of you will want to subscribe.
The Wonder of Fuel Maps!
We need a way to talk about fuel efficiency of engines and boats and by far the best tool for that job is a Fuel map such as the one here from Wikipedia. These are also called Efficiency Maps or Consumption Maps where the horizontal X axis is RPM and vertical Y axis is Torque typically expressed in BMEP (Brake Mean Effective Pressure”). This allows you to plot out colored lines of a given engine’s specific fuel consumption usually measured in units such as grams per kilo Watt hour g/kW/hr or grams per HP hour g/HP/hr and these colored lines are like a topographical map but instead of elevation of land, each curved line is a given amount of fuel consumption.
What is super helpful about Fuel Maps is that the specific fuel consumption lines are normalized so you can compare any two engines of any size because the lower the specific fuel consumption number, the more efficient the engine will be at that combination of RPM and torque. Does not matter if this is one of the world’s largest diesel engines such as the 14 cylinder Wärtsilä RT-flex96C that can produce over 100,000 HP @ 102 RPM (not a typo!) or a slightly smaller 2 cylinder Beta 10 engine that produces 10HP @ 3,000 RPM, you can directly compare their Brake Specific Fuel Consumption BSFC numbers.
Show Me the Money (numbers)!!
I know this has been a long and winding journey to get here and many of these acronyms and metrics can be overwhelming so let’s put this into more understandable every day units we can all understand.
While it may be counterintuitive to many the Wärtsilä RT consumes 171 g/kW/hr and the Beta 10 consumes about 330 g/kW/hr. Converting these numbers to efficiency, the Wärtsilä has a thermodynamic efficiency of 48.1% and the Beta 10 works out to about 24.8%. So as surprising as this may be, the Beta is about 50% less efficient and consumes twice the amount of fuel relative to its rated power output. Clearly I am choosing extreme examples as the Wärtsilä RT engine has held the record for the most efficient diesel engine in the world and it does weighs in with a dry weight of a svelte 2,300 tons so there is that, but you get the point of how handy it is to work wtih these BSFC.
Oh, and for those wondering, Mr. Gee, a Gardner 6LXB has a BSFC of 206 g/kW/hr which works out to be no less than 39.73%. If the engine is operated slightly below maximum torque, it does attain slightly more than 40% thermal efficiency. Now you can see why we chose to marry Mr. Gee to a CPP bride for truly outstanding efficiency, longevity and low maintenance,
If you’d like to know more about Fuel Maps, Matt also wrote up a very good explanation of these in his other post “Understanding an Engine Fuel Maps” HERE and reading that will help you understand what I’ve written below much better.
Fuel Maps for CPP driven boats
I will leave you to digest all these articles and charts above at our own choosing and speed but to get to the crux of it for our discussion of CPP props I will focus on the following 3 following three Fuel Maps from Matt’s great article above.
Here is an example of a “fuel map” that Matt created for his articles. This would equate to a typical 4L 100kW/135HP four stroke diesel engine. The thick Red line is peak Torque and the green circle is the sweet spot of fuel economy, power and torque we seek.
When we add in the Blue/Purple line of a Fixed propeller torque curve, the problem becomes very easy to see; the optimal green circle is a long ways away from the middle of that center Goldilocks Island we want and the prop torque curve never even gets close to Goldilocks Island at any RPM. With a FP this is just the way it is and there isn’t much you can do about it.
However, if we change to a Controllable Pitch Prop we can “pull” the green circle over here simply by changing the pitch and we now run right though that Goldilocks sweet spot! Being able to change the Pitch allows us to drag that torque curve pretty much anywhere we want it
I can imagine that some of you might feel that I am overstating the situation with FP boats to lead into the explanation of why we chose to go with a Controllable Pitch Prop or CPP, and perhaps I am. But all of these points above are based on the laws of physics to a large degree and just the way a FP and diesel engine works.
You might think about it this way; in a FP boat there is only one way that you can change the speed of the boat in a given set of conditions and that is by changing the RPM of the engine and prop. That works BUT these are often RPM’s that are much less efficient and you would otherwise not want to use if you had a choice. Turns out you do!
The ideal would be to be able to run your engine and prop ALL the time under ALL conditions, at their just right load conditions where they are most efficient fuel and power wise. As it turns out this isn’t all that difficult to achieve if we simply add the ability to change the pitch of the propeller at any time such that the engine is always running at its just right RPM and the boat is moving at whatever speed you want within its range. This is what a CPP does: just right load at any RPM and SOG (Speed Over Ground)
CPP props are not new or uncommon having been in daily use in boat airplanes and boats around the world for almost 100 years. For example almost all propeller driven airplanes have a CPP. Have you ever wondered how such a plane can sit there on the runway with its propeller/s whirring away and not be moving? Simple, the pilot adjusts a lever in the cockpit that changes the pitch to zero such that it is like a knife slicing through the air producing no thrust. When you’re ready to take off you just push that Pitch lever forward, the prop blades rotate more and more, producing more and more thrust and the plane zooms down the runway. Once the plane is in the air and finished climbing, the loads are much lower so you reduce the pitch accordingly.
Change the medium from air to water and the CPP in a boat works just the same way. Here is a short video that might help you see how a marine CPP works and looks as it is changing the pitch.
But Wait! There’s more!!!
Below is a short video of Uğur manually rotating our four bladed CPP on Möbius. This is from last year during the build but does a good job of showing you just what is going on under the water as we move our Pitch lever on Möbius.
There are several additional benefits that might not be immediately apparent until you get to know CPP a bit better and one of the biggest benefits worth pointing out is that if you can change the pitch from zero/neutral to full ahead, you can do the same in reverse by simply rotating the blades the opposite direction AND the shaft continues to rotate in the same direction.
Thus you eliminate the need for a fwd/rev transmission. You do still usually need a gear reduction box, ours is 3:1, to get the prop spinning much slower than the engine but no forward/reverse gears are involved. This has several positive consequences such as being much “kinder” to the engine and gearbox as there is no “clunking” in and out of gear and the other is that you can smoothly feather the prop from forward to reverse moving the boat just millimeters at a time if desired, which is eXtremely handy when maneuvering in close quarters, docking, etc.
Know the Load!
Just a very quick diversion to explain an eXtremely useful gauge on any boat and one that is of particular value on a CPP based boat and that is having a high temperature thermometer known as a Pyrometer or an Exhaust Gas Temperature EGT gauge. If you’ve been following along for the past few threads about engines, power and fuel consumption you will have noticed that the key metric that efficiency is based on is the % of load you are putting on an engine. To avoid confusion, keep in mind that Load is the power in either kW or HP that you are USING at any given time and NOT the total POTENTIAL power an engine can produce. Also keep in mind that load can not be measured by RPM, you can fully load or over/under load an engine at ANY RPM. Therein lies the challenge; If you can’t go by the RPM’s on the tachometer or the throttle position, how do you know what the load is at any given point?
It turns out to be rather simple to know the load when you understand that exhaust gas temperature or EGT is a direct proxy for load because as the load increases in a diesel engine, so too does the heat of the exhaust gas. Measuring the EGT is done very simply by having a thermometer that can measure high temperatures which is technically called a Pyrometer and what I will refer to here as an Exhaust Gas Temperature gauge. Very similar to what you might have to check the temperature of your oven or a meat thermometer, you insert a probe into the exhaust manifold, usually at the end or elbow where the exhaust is exiting the manifold.
My finger is pointing at the threaded fitting I have installed at the end of the exhaust manifold on Mr. Gee I am using a Maretron EGT probe as this makes it easy to put all the EGT data onto our N2K/NMEA2000 network that allows us to display the EGT gauge on any screen, anywhere, anytime. Installation is as simple as putting in the threaded adaptor that comes with the EGT probe, inserting the probe, tightening the nut and then connecting the wires into your N2K network.
There are also many gauge companies who make independent EGT gauges that just wires the probe to a dedicated display on your dashboard the same as you would do for things like oil pressure, oil/water temperature, RPM, etc.. Here is one example of a test setup Christine made to display EGT and Fuel Burn rate on any of our screens while we were doing our initial sea trials in July. For those interested, this is an example of some of the various ways we can chose to display our engine and boat data on our Maretron N2KView screens. You can have as many of these screens as you have time to create and this one is an example courtesy of our friends James and Jennifer on mv Dirona. OK, now that we know the exact EGT and therefore engine load at any given time, it is easy to adjust the Pitch lever to the Goldilocks load and efficiency we want at ANY speed and in ANY conditions. This is a significant advantage to any boat I would think but it turns out to be an eXtremely Big Deal on an XPM type of boat and use can in particular.
Why Does this all Matter?
If I have done a reasonable job of brining you this far, you now have a good answer to that question as the CPP enables us to operate near peak efficiency under almost any conditions and this adds up to significantly better fuel economy and lifespan for the whole propulsion system on any boat. Now put this in the context of an XPM style of boat that is intended to allow a couple to take their floating home across oceans to the far reaches of the seas which means that these boats will be underway on long passages running non stop for weeks or more and complete self sufficiency throughout their journeys. Therefore these boats have unusually large tank capacities for both fuel and water which adds up to a lot of weight that literally comes and goes over these passages and so the displacement (weight) of these boats changes a great deal from start to end of passage and over the course of a year. Thus the boat has a highly variable displacement and when you add into this equally as variable wind and sea conditions, an XPM’s propulsion system must bee able to handle ALL of these varied conditions and do so while continuing to be optimized for all of the Safety/Comfort/Efficiency/Maintenance priorities.
XPM liquid loads vary substantially during a passage and over the annual use of the boat and to put that into perspective, our total fuel tankage is 14,617L/3861USG = 12,410Kg and water is 7300L/1930USG = 7300 Kg/16100 Lbs for a total of 19,700 Kg/43,450 Lbs. That is a LOT of weight and amounts to the displacement of the boat changing by over 55% ! That is a huge range that the propulsion system needs to be able to deal with efficiently throughout and this is yet another way in which the CPP provides significant advantages. Being able to change the pitch in synch with the changes in overall displacement of the boat as the fuel and water volumes go up and down allows us to stay in that Goldilocks sweet spot on the Fuel and Efficiency Map ALL the time.
System Based Solution:
Another key benefit that helped convince me that CPP was the way to go for Möbius is that the CPP comes as an integrated solution. With a FP you typically need to spec, chose, install and buy each component; the FP itself, then a matching prop shaft, then cutlass bearings, prop tube, flanges, transmission, shaft seals, anti vibration mounts, Elecrical controls, and the list goes on.
In our case, we chose to go with Nogva a large Norwegian company that builds complete propulsion systems. They provided us with everything except the engine as we already had Mr. Gee, though Nogva does offer several major engine options from the likes of JD, Scania and Nanni.
We worked closely with the engineers at Nogva to provide them with all the details of the boat and how we wold be using it and came up with a propulsion system that consisted of their N4-215-65 CPP system that looks like this and includes literally every part you need from the prop at one end to the flange that bolts to the servo gearbox at the other. Installation of the whole prop tube and shaft assembly Nogva shipped was eXtremely easy as we just inserted the Nogva prop tube into the aluminium shaft log pipe that had been welded in as part of the hull months prior. These two tubes slid into each other with about 10mm / 3/8” clearance between them so it was a simple matter of aligning these two shafts concentrically and then pumping the space full of ChockFast an epoxy filler made for this job.
The bright red flange you can see on the far Right here is that flange on the N4 CPP which I am not bolting together with the brown Nogva HC-168-C servo gear reduction box using the standard SAE1 flange on the back of Mr. Gee which is the Silver/Aluminium part on the far Left.
I can not overstate the benefits of getting the entire propulsion system as a complete system from the same manufacturer as it made both the installation and the maintenance of this critical system eXtremely easy and reliable.
Additional Benefits of CPP
This does not apply to us on Möbius as we went all electric, but for boats that have hydraulic systems for things like thrusters, stabilizers, windlasses and winches, CPP provides a significant advantage in that not only is the pitch always just right for actual load, it also provides the ability to have higher engine revs needed for the hydraulic pumps even when you are docking or stopping the boat. With a FP it is challenging to keep the engine revs up just as you need that bow thruster and winches the most while the boat is near standstill while docking.
Slow Speed Maneuverings
Speaking of docking, with a CPP you can move the boat with silky smooth precision 1mm forward/astern with nothing more than small movements of the Pitch lever forward/aft.
Repairing Broken Props
Given our intent to cruise in icy locations in high latitude locations, as well as the always present danger of an errant underwater log or coral head that can take a bite out of your prop blades, the CPP provides a much more manageable repair than a FP. With a once piece FP if you bend or break a prop blade the whole propeller needs to be removed, often the shaft along with it and have it repaired or replaced by an all new one. I have had to do this on previous boats and it is a big job that takes a lot of time.
With the blades on a CPP being separate parts and the center hub being much stronger and more robust, it is relatively easy to remove and replace just one or two prop blades and this can be done while the remains in place.
When I spoke with the Nogva engineers about this scenario they agreed to machine an extra set of four blades in the same run and were able to provide these at a very low cost. I carry these four new blades along with a set of O-ring seals and grease just in case this should ever be a repair I need to do in some far flung spot. To fully validate all this and give me some advanced practice in such ideal conditions, I did a trial run by disassembling the prop and removing all four blades. It turned out to be a very quick operation with no special tools required.
I started by removing the eight SS Allen head SS bolts you can see here which let me easily remove the end side of the hub. This now exposed the bases of the four blades which rotate around the square bronze block you see in the center. Each blade is machined to precisely slide into place on the boat side of the hub and then the end side hub fits over that to fully capture the props. A rubber O-ring around the grooves you see here, seals each blade to keep the water out and the grease in. Some of you have asked “Isn’t this a very complex piece of equipment?” and while it can’t get more simpler than a single part fixed prop, these CPP props really are not complex at all.
And when you consider the whole propulsion system not having any gear changing transmission reduces the overall complexity considerably further. When you slide the blades off the only thing that remains inside is the end of the SS Pitch Adjustment rod and the single bronze block that each blade pivots on. No gears, no bearings, just a lot of grease. Slide each blade back in place, bolt the end cap back in place and you end up with a fully operational CPP. Before we splashed the boat back in February we of course put on the black International InterSleek silicone based Foul Release paint an all the underwater aluminium surfaces and coated the Nogva CPP with similar silicone PellerClean. Now seven months later with very little movement unfortunately, the good news is that there is almost no growth on either the CPP or the bottom surfaces and what little we’ve found comes off easily with a simple wipe with a cloth.
In my discussions with the Nogva engineers and other research before making my decision to go with a Nogva CPP, I was impressed by the attention Nogva had paid to the problem of prop blades transferring noise and vibration into the hull. As I understand it, Nogva provides propulsion systems for work boats used in aquaculture and the use case of these boats in particular need to have robust, efficient and reliable propulsion in their very demanding situations.
Like XPM’s these work boat hulls are usually made of aluminum, which can be prone to noise and vibration problems. Nogva’s solutions counteract these problems by minimizing the propeller’s impulses toward the hull.and they have gained a lot of experience though their R&D into this. I will need to get more nautical miles on our Nogva CPP to more fully understand how well this all works but based on our sea trials to date, the whole propulsion system is very smooth and working very well so far.
OK Wayne, but What about Cost?
This is perhaps the most asked question or concern when others are considering FP vs CPP for their boat. For those considering changing their current boat from fixed to CPP it would be a move costly conversion in terms of both time and money and I don’t think the payoff would be there. However the opposite is the case for those of us building a new boat where everything has to be purchased and installed either way. In this case the CPP turns out to be no more and some have suggested less total coast than a fixed prop.
Perhaps the best explanation of this is a very thorough comparison that Michael Kasten’s did and wrote about in that article I mentioned up near the beginning. HERE is that link again to save you from scrolling up to find it. Michael did this research back in early 2001 so the actual amounts he quotes have of course changed, but based on my more recent research and purchasing all the costs have scaled up equally and so I think his examples still hold up. In the beginning of this article Michael does a good job of providing an overview of how CPP props work and why he too sees them as a better and more efficient type of prop for the boats that he designs, but if you scroll down to “Part II Costs” you will find his comparison of pricing out a like for like Fixed Prop and a CPP.
Near the end of this comparison he goes on to cover some of the same points I mentioned above as to the cost and labour required to install a CPP vs a FP. He arrives at the same conclusion as I have with is that installing a CPP system is actually less time and effort than a FP. Installation wise there is little to no difference between installing a transmission for a FP vs installing a servo reduction gearbox for a CPP so that is a wash cost and difficulty wise. However installing a CPP shaft system is much easier than the more “distributed” FP components.
Michael ends with names and links to all the CPP manufacturers he was aware of at the time and these will provide those interested with a good starting point for doing their own research.
I had read Michaels article several years ago before we Möbius was even a twinkle in my eyes and so I referred back to it and used it to help me do my own research and comparison of the pros, cons and costs of FP vs CPP and I came to the exact same conclusion that a CPP is no more expensive or difficult to buy and install than a fixed prop and could be less. Given the significant advantages and benefits I’ve gone over up above you can hopefully understand why this became a “no brainer” decision for me to make. Nothing since then in our experience with buying, installing and now staring to use a Controllable Pitch Propeller has changed and it has already exceeded our hopes that this would be the Goldilocks propulsion system for Möbius. I fully expect that opinion will continue to improve over the entire time we are running Möbius and enjoying all these advantages of the increased Comfort and Efficiency our Nogva CPP provides as well as the significant reductions in fuel costs.
Isn’t a CPP Difficult to Operate?
Another of the most common questions I receive and so I will close out (bet you thought that would never happen!) by doing my best to answer this final question. A couple of quick caveats for context here. First there is no question that Christine and I are much more familiar with operating boats with a Fixed Prop and their typical Throttle + Fwd/Reverse levers or combined single lever versions. Switching over to CPP therefore presented us with some initial learning curve and at first it all felt very strange as everything was SO different. No “clunk” as we were used to when you put a FP into gear and you knew that the boat was going to move forward right away and increase speed as you increased the throttle and engine RPM. With the CPP there is no noise at all and the boat does not immediately jump forward, or reverse, and so at first you are a bit uncertain what is going to happen. You know the prop is turning at all times as you can see some of the turbulence coming out the sides even when you are in the Zero Pitch/Neutral position and moving the throttle forward increases the engine RPM but the boat just sits there. However, as you push the Pitch lever slowly forward in absolute silence and lack of any other indication, you notice that the boat is indeed moving forward and the more you push the Pitch lever forward, the faster you go. Pull the Pitch lever back and you very quickly slow down but again no other indication other than the visual confirmation of gauges and surroundings that you are slowing down and stopping.
We both spent some time out in some calm open waters to try out this all new propulsion control system and the strangeness soon faded away and began to feel more and more intuitive. Set the RPM where you want them and then increase the Pitch to move forward or reverse with extremely smooth and strong control.
Our first few experiences with docking this all new boat would have been challenging enough so with the added newness of a CPP it was all the more so. However all the surprises were very good ones as you were able to so smoothly and completely control the movement of the boat. With a very big four bladed of just over 1m diameter and an equally large rudder controlling the stern of the boat while docking is like having a stern thruster. We also have a very powerful electric bow thruster and as we have practiced using the combination of these fore and aft controls we have already gained a lot of confidence in our ability to control Möbius while doing such close quarter manoeuvring and even more so when we get underway. All still VERY early in our learning process but it has been a great start so far.
So the best answer I can provide at this early stage is that there is no question that learning to operate a CPP does take some time but it is time well spent and I’m not sure that this is very different than any system on a boat. Like all our systems, It takes a bit of time to learn where the sweet spots or Goldilocks settings are and become familiar with them so they become routine.
Operation of the CPP for cruising can be done in two different ways; set the Pitch and adjust the throttle to reach optimal loading of the engine or do the opposite, set the Pitch to where you have learned you think it will be best and then use the throttle to move you up to whatever speed you have found to be optimal for a given set of conditions. As I’ve covered in the sections up above about EGT we have learned that we basically run the boat based on the EGT reading once we are at the speed we want. We are learning to watch the EGT numbers to be sure we stay well below the maximum EGT/load which in the case of our Gardner 6LXB is about 450C/840F. If the EGT number gets too high, just back off the Pitch a bit. At this setting, the engine is powering the prop at its maximum ability, and runs well loaded at max. efficiency.
You don’t want to set the pitch too shallow as the engine will not be loaded by the prop and will run straight up to its maximum rpm. Nor do you want to set the pitch too steep either for the given rpm as that will overload the engine. Dark smoke and a increasing EGT are a signal for overload. In situations where you want to be moving much slower, you set the RPM lower and the Pitch higher to load the engine sufficiently at low power range and low fuel consumption. In opposite situations when going uphill in adverse weather we will set the RPM higher and the Pitch lower or more shallow to allow the engine to come up to speeds with higher power output. The recommended practice for docking with a single prop vessel is to set the RPMs higher rpm (about 60 to 80%) and then use the Pitch lever to do the needed and often hard over manoeuvres. We are learning to trust that we can push or pull the Pitch lever in either direction at these higher revs and it does not harm the system. This is quickly feels very comfortable as you experience the eXtremely fine control you have over moving the boat incrementally or quickly with just the Pitch lever.
Clearly I am in NO position to be offering advise here about running a CPP well and how to best handle a CPP powered boat, but these are my early lessons learned and I look forward to bringing you more and more as we get out there and log more hours and nautical smiles on Möbius.
Whew!! If you have made it this far, you are probably almost as tired from reading all this as I am from writing it. But even if it takes you, and me, more times to re read this and learn more, I do hope this has at least been interesting and informative for you no matter where you are at in the comparison between Fixed and Controllable Pitch propellers.
I will sign off for today with a “proof is in the pudding” shot of the stern wake we leave behind us while doing 9.2 knots at 1500 RPM burning 21.7L/hr EGT @ 305C.
VERY happy with how well Mr. Gee and his Nogva CPP bride get along and how they propel us with such eXcellent Safety, Comfort, Efficiency and Maintainability.
Thanks for coming along for this long and winding ride and please join the discussion by adding your comments and questions in the box below.
The cooling trend continues with the weather here in Finike Turkey as the daytime highs drop down below 34C/93F most days this week and the forecast calls for our first sub 30C/86F high next week. We are very fortunate in that we have a huge swimming pool here at Finike Marina, aka the Mediterranean Ocean, that is just a short walk down along the sea wall from where Möbius is docked. We are able to have our nightly swims thanks to a set of stairs up over the sea wall that the Finike municipality put in several years ago.
You can see more of our nightly swim spot in the fun video HERE which Christine put up last week of her first solo piloting of our Mavic Air 2 drone. So every evening around 7pm or so, we exchange our work clothes for our bathing suits and make the short walk down to this set of stairs up over the sea wall every evening after we stop working and swim off this landing for 15 minutes or so. We even a fresh water shower to rinse off all the salt on our way back to the boat.
Oh! AND we also have the AirCon working very well now for those days that are still a wee bit too warm, so we are very comfy and grateful to be here. I am running late here getting this blog written on Sunday afternoons as usual and it has been another very busy work week getting more and more of the jobs done on Möbius but I’d like to share some details on a set of related topics which I get asked quite about very often and which seems to be surrounded by SO much confusion and misinformation; Power, Load and fuel consumption.
What moves a boat?
Seems like such a simple question, and the answer really is equally as simple and yet, in talking with other boat owners over the years, both in person and online in various forums such as Trawler Forum, I’m often surprised at some of the things I hear otherwise very savvy and smart people say when it comes to things like Horse Power, fuel consumption, propellers and other aspects of the propulsion of their or other people’s boats. I was reminded of this again just this week by a post that Steve D’Antonio sent out in his August 2021 Newsletter “Full Throttle vs. Full Load”. If you are not already subscribed to Steve’s newsletter I recommend it highly as a super valuable source of very thoughtful advise and info on all things boating.
In this most recent article, Steve goes over the often confused differences between full throttle and full load and more importantly he links to a much longer and well written article of his called “Wide Open Throttle” from back in 2010 for Professional Boat magazine which I also recommend eXtremely highly if you are not already subscribed (free) as ProBoat is one of my best learning resources and I have their entire library of magazines.
Both of these articles are must reads in my opinion if you would like to understand the relationship of HP, fuel burn and power going to your propeller. However THE best explanation of this relatively simple set of relationships is written by Tony Athens at Seaboard Marine in his very well titled article “Propellers Move Boats, Engines Just Turn Them”. All three of these articles are very much worth your time and I will circle back around from what they address in a future article here to talk more about why we have a Controllable Pitch Propeller or CPP on Möbius. It will also address why we chose to have a Gardner 6LXB turn that CPP
Once you have read these over I think that you will clearly understand what so many don’t seem to. The major points are as follows:
The rated HP of any engine tells you very little about the amount of fuel it will burn or the load that engine will be running at.
When I am having these discussions my key point is that HP = amount of fuel burned, full stop, no other information or variables required.
However, to quote a much fuller explanation from Tony’s article the single best relationship to understand is “… the amount “FUEL BURNED” is the amount of “HORSEPOWER PRODUCED.” That is the COMMON DENOMINATOR, not ENGINE RPM, and NOT the actual rating of the engine. And, what makes the engine produce a given amount of horsepower is how the propeller loads the engine.”
Using one of the example’s Tony uses near the end of his article, if you have the same make and model of engine in two identical boats, but one is set up by the factory, to BE ABLE TO reach a maximum of 300 HP and the other boat with the same engine is set up by the factory to reach a maximum of 715HP, when these two identical boats are running side by side, their fuel consumption will be the SAME because the amount of HP that the boat requires is also the SAME.
Load can be very deceiving because it is based on the RATED HP of that engine and has very little to do with how long an engine will last. (assuming it is not overloaded). As Tony outlines in his article, you can set up the same Cummins QSM11 300HP to 715HP, for the otherwise exact same engine. So if the propeller requires 215HP to move this boat at a certain speed and set of conditions, then the load gauge on the 300HP engine would read 72% whereas the 715HP version would say the load was 30% and BOTH engines would last or have the same amount of “wear and tear”. So contrary to very popular opinion, load % has very little to do with how long any marine engine will last.
If this does not make sense to you, or you have always been told otherwise, please do give these articles above a read and then let me know in your comments if you still think this does not make sense or is not correct. Once we all have the same understanding of these basic components of boat propulsion and how they are related to each other, I will address one of the most asked questions I receive; why did you chose to use a CPP on your boat?
I know these more technical topics are not everyone’s cup of tea, but for those it is, I hope you enjoy the articles above and I look forward to any additional discussion or questions you have.
Sorry that I wasn’t able to write up this weekly update and get it posted on my “regular” schedule of each Sunday and I’ve kept you waiting till now but hopefully the wait will have been worth it as I take you on a deep dive into the DC charging system on Möbius.
On Sunday, Christine and I took the afternoon off to go explore some of the area around our new “home town” of Finike, which is something we should do more of I’m sure as boat and book work completely consumes us otherwise. We have rented a little Fiat minivan for a few weeks so we wanted to take advantage of that and my super researcher partner had found a cool sounding little restaurant on a river about 20 minutes drive away from the coast here. It was a wonderful treat for us both and we spent the whole afternoon sitting at this table for two at this tiny little restaurant on the riverbank in an equally tiny little village off a side road. You can see that I timed the shot to catch one of the kids jumping into the cool waters that the village had created with a small rock dam to slow down the flow. We have found several of these little riverside restaurants during our years here in Turkey and this one was the Goldilocks just right, just for us being so small and remote.
Fresh roasted trout dinner with the full compliments of fresh salads, fries, Turkish baked bread and sauces plus a well chilled bottle of Merlot made for the perfect getaway afternoon for us both. Total bill was an exorbitant USD 30 but heck, we’re worth it!
We weren’t the only ones chillin’ ourselves waterside as Barney enjoys his very own pool on the aft deck where he can survey his Kingdom while staying well hydrated.
Yes, that’s the bow of our Tender “Mobli” which when on deck serves double duty in providing the shade for Barney’s pool.
Möbius’ Charging System Trifecta
Back in September 2019 I wrote the first Tech Talk to outline the overall design we came up with for the Electrical System and this is an updated version of the schematic I created of the overall system.
As per this week’s title I believe that we have put together the perfect trifecta of components to make our Goldilocks 24 Volt charging system consisting of;
24 x FireFly Carbon Foam 4v cells
Just 10 of them shown here and these have been well covered in many previous posts.
2 x Electrodyne 250A @ 24V AC PowerHead E250-24 alternators with remote rectifiers mounted out in the Workshop (see photo below)
2 x WakeSpeed 500 Smart Regulators with the 2 red remote Electrodyne rectifiers mounted alongside
I have written several articles in the past as these components were being installed and if you’d like more details on that here are links to some of those past postings:
NOTE: Just to be clear for anyone who might wonder, Christine and I have purchased all of the equipment I’m discussing here and none of this has been sponsored or otherwise paid for. indeed this is true for ALL of the equipment on Möbius and covered in this blog. We are simply BIG fans of companies who produce products that really work in our eXtremely real world and especially the people at these companies who stand behind their products from the beginning of our work with them to design systems, install them and all the way through to their support as we move into commissioning and putting all these systems to work.
So we are delighted to feature such products and the people behind them here on the Möbius.World blog.
Meet Big Red #1 & #2
As I wrote in those past posts, I’d known Electrodyne alternators since I was working as a HD construction mechanic in my youth and Electrodyne alternators were the ultimate choice for large construction and mining diggers, railroads, trucks, busses, emergency vehicles where they often ran 24/7 for weeks or months. They are literally built like tanks and each one weighs 40kg/90 lbs!
I had initially worked with Pete Zinck until he retired in 2018 and turned things over to his Production Manager Dale Gould and who could not have been more helpful and responsive to my many Emails and requests.
As you can see Dale is also a very hands on guy! Here he is making the final checks and tightening the remaining nuts on finished alternators awaiting packaging.
Dale continues to be super supportive as I commission the whole charging system on Möbius and I can not recommend Electrodyne and Dale highly enough.
What we ended up choosing are two identical Electrodyne E250-24 models which are de-rated down to 250Amps @ 27.5V @ 3750RPM which would give each one a maximum output of almost 7kW (6.875) for a combined output of almost 14kW. As I covered in last week’s posting about the drive systems for these massive alternators, I chose some ratios for the pulleys such that their max speed will be about 3200-3400 RPM for even longer life.
These “PowerHead AC alternators” have several unique characteristics that made them just right for me and Möbius:
Brushless so no brush springs or brushes to wear out
One moving part (rotor)
Everything other than the rotor is external; No built in regulators, No built in rectifiers.
Why go to such extremes? In a work; HEAT, which is the largest factor in shortening an alternators output and lifespan. Rectifiers can produce more than half the total heat within an alternator so by removing these and going with industrial grade 3 phase bridge rectifiers I can reduce the internal head of the alternator by more than half AND control the heat of the rectifier bridges outside the ER and with their own fans.
With only one moving part, the spinning rotor so MUCH better airflow through the alternator stator windings and rotor. The Goldilocks alternator for an XPM; consistent high output with low heat and low maintenance.
Each PowerHead is “double headed” housing two separate AC Alternators inside, one on each end. Having two of these Electrodyne units means we have 4 alternators in total.
With no rectifier or regulator built into them, each PowerHead only puts out AC current, everything else to convert this AC current to DC is external.
As you can see in these photos, there are six large cables to carry the AC output out of the Engine Room and over to …… …… these two red external rectifiers which are mounted outside the Engine Room under one of my AL Workbench tops with thermostatically controlled fans to ensure they are always running nice and cool and at maximum efficiency. All the heat Mr. Gee generates stays in the Engine Room which is why I designed the ER to be just that; and ENGINE (only) Room.
Q&A with Dale Gould from Electrodyne:
** Feel free to skip to the end of this section if you are not interested in a deep dive into the inner workings of how these Electrodyne alternators work.
For those of you interested in more details on the unique way these Electrodyne PowerHeads work, I asked Dale a series of questions and he kindly answered them as follows. I’ve added some photos I took when I was taking these alternators apart and painting them, to help illustrate these Q&A.
** Before you ask, Yes, of course I took these Electrodyne alternators apart! When I don’t understand how something works or I am otherwise curious, this is what I do.
Wayne’s Q: In working with the two Electrodyne E250-24 PowerHead alternators you built for us, I’ve noticed that they are built quite differently that any other alternators I’ve worked on. Can you tell me a bit more about how you build these and why?
Dales A: When looking at the inside of an E250-24 you will notice that the Electrodyne’s are built completely opposite of a normal alternator. The rotor spins around a stationary stator rather than the rotor being inside the stator (Claw tooth design). The reason we do this is to achieve more power. By having a larger stator inside the unit that can hold larger sized wire we can achieve higher outputs. We have fine-tuned the size of the magnet wire to the amount of turns per coil to achieve certain outputs at various voltages. We also use an individual lamination stack made up of either 54 or 64 laminations depending on unit and voltage. This helps us reduce eddy currents and allows us to dissipate heat more efficiently. This method is also used in our rotor lamination stacks. Wayne’s Q: I understand that these are permanent magnet or PMA alternators so can you tell me why there are still Field Coils and what their role is? Dales A: The field coil is essential to all units as it works in tandem with the stator to achieve the voltages, output, and current desired. Each field coil has also had extensive testing with different turns of wire at different thicknesses for the highest performance. Even though the rotor has magnets in it a field coil is still necessary. The field coil is what supplies the magnetic field in the alternator. On certain alternator applications such as yours, Electrodyne will add permanent magnets to the rotors to aid in additional magnetism to achieve higher outputs and a lower turn on speed.
Wayne’s Q: Most alternators, even high output ones I’ve used in the past, their cases are typically made from aluminium and are much smaller and lighter than these beautiful cast iron beasts you make. Can you explain the reasoning behind this? Dale’s A: The housing we use is cast out of ductile iron for two reasons. Extreme durability and magnetization. When the unit is first powered on and magnets are introduced to the rotor, we magnetize the housing. This also contributes to higher outputs as the whole housing now acts as a magnet itself. Electrodyne uses an insulated grounding method for its alternators so nothing goes to ground unless specified by the customer. Having an insulated ground system allows for the Electrodyne’s to be either negatively or positively grounded.
Wayne’s Q; I chose to go with your Electrodyne alternators largely because you not only removed the regulators but the rectifiers as well so I can mount these as separate units outside of the alternator cases and outside the Engine Room. The rectifiers like this one here also have their own thermostatically controlled fans. This dramatically reduces the amount of heat being generated inside the alternator cases but there is still some, so how do you keep these PowerHeads running even cooler and for so much longer than other makes?
Dale’s A: The rotors of an Electrodyne alternator act as two large fans. There are holes plotted along the casting of the housing that act as breathers.
Photo Dale provide from the Electrodyne factory showing the rotors being machined.
The fan spinning will pull air from outside and cool the two major components of the alternator (stator & field coil), simultaneously ejecting that air out and keeping the inside free of excess heat buildup.
Another way the alternators deal with heat is by switching the field on and off (pulsing the field). This turns the field of the alternator off to allow free spin when a load is not required. The rotors are also bi-directional. They will cool the unit with either directional rotation an engine uses. Finally, on a remote rectifier system like yours, we remove the diodes from the top of the alternator and give them their very own fan cooled housing. The E-2281 is mounted with a fan that keeps the diodes cool while under load. The diodes used on Electrodyne’s are extremely important and need to be able to withstand constant abuse. The diodes act as a check valve for electricity, turning the AC current the alternator produces and eliminates the back and forth alternating current to a straight-line direct current. Our diodes are rated to a 900-ampere capacity and offer a high load dump capacity as well. Ensuring that electronic equipment such as regulators are not damaged when the unit is powered down. Wayne’s Q: As I looked more closely I can see that these PowerHeads are not just heavy in weight they are truly Heavy Duty as well. With our focus on Maintenance (Lack thereof) and longevity this was another big factor in my choosing to go with Electrodyne alternators so can you give me some details of how you have designed and built these alternators to be so long lasting? Dale’s A: The Mechanical parts Electrodyne uses are made for longevity. The bearings used are class 3 ball bearings and needle bearings that have a 20,000-hour rated life. The reason we use such long lasting mechanical components is for duration of life for the alternator. When an Electrodyne is purchased peace of mind should go along with it. Minimal failure rates are key to the Electrodyne advantage. With a brushless design we can eliminate parts from wearing over time.
Mounting the Red Monsters:
If you read last week’s post you know all the details of how I’ve designed and mounted each Electrodyne to be driven differently so here is a quick summary.
Big Red # 1 is up top, resting on the large flat mounting surface cast into all Gardner 6LXB Crankcases and then driven by a cogged tooth rubber belt being driven by the crankshaft pulley. This drive setup has a 2.15:1 ratio, meaning that the alternator rotates at 2.15 times the RPM of Mr. Gee’s crankshaft.
Big Red # 2 is down lower where it is bolted directly to the side of the AL crankcase to align with the gear driven PTO or Power Take Off on the bottom front corner of all 6LXB engines. I modified a jack shaft to connect the two very solidly together as you can see here. The drive ratio for this alternator is fixed by the internal gears driving the PTO shaft at 1.80:1 so this alternator #2 will spin a bit slower than #1.
No Generator = Best Generator?
I am often asked how Möbius can be completely self sufficient electrically without having at least one if not two stand alone diesel generators as would be typical of most other passage making boats and trawlers. First part of the answer is that the 4.48kWh from our 14 solar panels is enough to keep our 43.2kWh battery bank fully charged most days and the second part is that if not, the combined output of these two Electrodyne alternators are able to add up to 12kWh of their own.
Designing our charging system this way eliminates the need for a separate generator and aligns perfectly with our SCEM priorities of Safety/Comfort/Efficiency/Maintenance to give us the best generator of all; none!
To be fair and technically correct I guess it can be said that we do in fact have a generator onboard, and a 12kW one at that! Just not in the traditional sense nor with all the traditional cost, noise and maintenance.
Electrodyne Output Details:
I’ve received quite a few questions about the numbers behind our charging system so let me provide the following info to help answer these: Here is a scan of the graphed results of the test runs that Dale did at Electrodyne of our E250-24 PowerHead alternators.
(Click to enlarge this or any other photo)
Using this graph I can see the output of each alternator when they are spinning at any RPM as well as how much power they need Mr. Gee to provide to do so.
Using those numbers, I have put together this simple spreadsheet to show the output of each Electrodyne alternator when Mr. Gee is spinning them at different RPM’s and the combined total output at the bottom. For example, when Mr. Gee is running at 1000 RPM, we have a total output of 363 Amps @ 24 Volts or 8.7kWatts and at our typical cruising speeds he is running at about 1500 RPM and there is up to 478 Amps/11.5kW available from the two Electrodyne alternators. Hence, anytime Mr. Gee is running, we have more charging power than we would ever need whether we are in tropical climates or the polar regions.
The Secret Sauce: WakeSpeed 500
I very purposefully refer to our charging setup on Möbius as a SYSTEM and each of the three components of our system are important and neccessary members of the team.
But what I think has really turned this into an eXtremely good system is the “brains” of the system; our two every “smart” WakeSpeed 500 Regulators. It is not at all hyperbolic to call these regulators “advanced” as they do on their cover and let me explain a bit more about why these are the true Goldilocks factor for our charging system on Möbius. And don’t take just my word for how truly revolutionary and smart these WakeSpeed regulators are! Here are some reactions from others MUCH smarter and more qualified than me as to how well these worked when they installed WS500’s on their boats:
“The notion of using current, as well as voltage, to regulate charging has always been the holy
grail for intelligent battery charging. With WakeSpeed Offshore’s new WS500 Advanced alternator
regulator, we now have that ability.”
Rod Collins — from www.marinehowto.com
“The WS500 also has a bunch of whiz bang features, but the cool thing is all most of us have to
do is install a shunt (if not already present) and replace our stupid regulators with this smart one
— and the even cooler part is that because this regulator is designed right — measures and
acts on net charge current — we don’t need to spend hours reprogramming it to get around its
John Harries — from www.morganscloud.com
Just as with Dale at Electrodyne it was the people more so than the electrons that mattered most. From the beginning, I was able to work directly with the two brains behind the smarts of WakeSpeed, Al Thomason and Rick Jones who created this amazing product. Al and Rick are both veterans of the marine charging world and are founders and inventors of WakeSpeed. Even better, Dale, Al and Rick all teamed up and worked together with me to do more testing on the combination of Electrodyne alternators being controlled by WakeSpeed 500 regulators charging FireFly Carbon Foam batteries! Does not get any better than that and I can’t begin to thank these guys enough for putting up with my incessant Emails and questions. Thanks guys!
The key features that make these WS500 regulators such a Goldilocks fit in our charging system are that they monitor and use a combination of system voltage, current in/out, alternator and battery temperature and alternator RPM to continuously adjust the Electrodyne’s to be the Goldilocks output for the FireFly Carbon Foam batteries at all times. Until WakeSpeed came along all our previous regulators could only use voltage to monitor and adjust the output of the alternators whereas the true indicator of what’s going on battery charge wise is the current (amps) going in/out of the batteries.
It was also not lost on me when I first started researching them several years ago, that WakeSpeed had already created custom profiles for FireFly Carbon Foam batteries and this was one of the examples that told me that these Carbon Foam batteries met my Tried & True test that I require for all our critical systems on Möbius or any XPM.
The other Goldilocks factor for our installation is that both my WS500 regulators can be “daisy chained” to work together and automagically synchronize the outputs of both Electrodyne’s by using both WS500’s to perfectly meet the needs of our FireFly house bank and everyone plays nicely together.
Sound difficult? It normally would be and would require additional relays or switching devices, but not with the WS500’s. All I do is plug a standard ethernet cable (white cable in this photo) into the RJ45 jacks in each WS500 and they become one big happy charging family.
Without going into too much detail here as there is lots available elsewhere that I will link to in a moment, it is the use of current (amps) going in/out of the batteries that adds the previously missing secret sauce to ideally optimized charging systems. Prior to these WakeSpeed 500 units, regulators were correctly called Voltage Regulators because that is what they monitored to control the charging output of an alternator. This obviously works because generators and alternators have been using voltage regulators for over 100 years to do their job. BUT, voltage by itself is not a very accurate way of determining the state of a battery and what we really care about is the amps flowing in/out of a battery to provide a truly accurate and just in time determination of what the batteries need from the alternator which ranges from everything they’ve got to nothing at all.
Some other great people have done a MUCH better job than I ever could at not only explaining their perspective on WS 500 regulators, they do so having installed these on their and other boats so they are speaking based on my favorite kind of knowledge; eXperiential. Here are links to these great resources so you can learn more from these others:
Steve “Seabits” Mitchel review and installation WakeSpeed WS-500 regulator review – SeaBits If you are not currently subscribed to Steve’s Seabits blog I highly recommend doing so. His articles are some of my most valued resources.
Last but not least, a big thanks to Rick Bell at Off Grid & Marine Energy Systems where I purchased our two WakeSpeed 500 regulators. Rick was a big help in answering questions and providing eXcellent after sales service for the WS Configuration Utility Pro version as part of my purchase.
WakeSpeed Setup: Have it Your Way
These WakeSpeed 500’s not only have the electronic smarts to do all of this, they have been put together in a package that I think is just brilliant. It can be as simple or as complex as you’d like to configure these regulators. For example, if you want to KISS the setup to your system, there are a set of 8 DIP switches inside each WS500 case and you just flip these to a pattern of On/Off and you’re done. Rick and Al and their crew at WakeSpeed also get a gold star from me for their documentation. NOT an easy award to get nor one that I am able to hand out very often I can assure you. For example, how well done is this Quick Start card?! Clear, concise, colour coded and shows you everything you need to know to connect and configure on one page! Connect the wires, set the DIP switches once and you can leave it at that for most installations. Adding to this already impressive feature list, WS500 regulators also provide me with these very valuable benefits that would otherwise not be possible or not easily obtained:
Adaptive Idle Technology™ which allows me to set the WS500 to control alternator loads based on
engine RPM. We can use this at both ends of the spectrum; when getting underway, doing close quarter manoeuvring and such we would typically have Mr. Gee at lower RPM’s and want all of his available power for moving the boat and don’t want or need any loads from the alternators. But if/when we want to add the output of the Electrodyne’s to our solar charging when at anchor, we can turn on our “Gardner Generator” by dialing up the loads on Mr. Gee at lower RPM’s to produce high outputs from the alternators to charge the batteries faster. This keeps both the batteries and Mr. Gee very happy.
Zero Output Technology™ enables the regulator to limit output to
loads when batteries require discontinued charging. This is particularly valuable for Lithium battery installations but this will be very handy with our large solar outputs when we don’t want or need any output from the Electrodyne’s when we are on passages.
More Goldilocks Gold
At the opposite end of the KISS spectrum, for those of us who might want to “geek out” more and really customize our charging system to be a truly Goldilocks setup, the WS500 regulators have more than 100 parameters that can all be adjusted and tweaked to get that just right, just for your boat’s charging setup. While this an get you “into the weeks” of minute details of charging systems there are several tools and utilities to make these adjustments relatively easy and quick to do. WakeSpeed is also to be commended for doing everything with open standards and being equally open themselves and we are already seeing a rapid growth in the number of companies making batteries, alternators and other components who are building custom profiles with all the specific settings for the WS500 to use. This method of having profiles, which are just small text files, that can be freely shared and easily uploaded into any WS500 via SD cards, USB cables, WiFi interfaces, etc. makes these WakeSpeed regulators a truly Goldilocks solution. You can see a list of some of these profiles and other technical documents HERE on the WakeSpeed web site.
Real World Data Coming Soon
I am still finishing up the final wiring of the WakeSpeed 500’s and the Electrodyne alternators so I have not been able to run this charging system and gather the real world data of all this at work; yet! But do stay tuned as I get this and the other critical boat jobs finished so we can take Möbius out on more trial runs and start to log all the data from this charging system and put some real data behind all this work to design and build our Goldilocks charging system. I’m waiting on some parts for Mr. Gee to arrive from the UK and complete a few other jobs that are keeping us tied to the dock here in Finike but I’m hopeful that we will be able to head out by the end of September and as soon as we do I’ll be posting updates for you that provide the proof of how all our systems are performing, including the charging system you now know all about.
Hope it was worth the wait of an extra few days for this week’s Möbius Update and that you found this latest posting to be of interest and value. Either way, I would be most appreciative of any and all questions and comments you can provide in the “Join the Discussion” box below.
Your Feedback Wanted: More Q&A type content and more Video?
On a related note, I’ve received some good suggestions that I start doing some Question & Answer sessions in some of these blog posts so if you have some questions that you would like to see me cover in a Q&A section, please type those into the box below and I will start to gather them together and post some answers to them in future blog posts.
I have also been receiving more requests to also start creating more video based content to cover the boat now that it is more finished and to consider including some Q&A sessions in those videos so let me know your thoughts on that and if there is enough interest, Christine and I will do our best to start creating more video content to post here and on YouTube.
But Wait!!! There’s more! Speaking of video content, if you have not already seen it, be sure to check out the great little video segment “The Drone Report” which Christine just published last week based on her first solo test piloting of our DJI Mavic Mini 2 drone. She’s a fabulous story teller in any medium and you can see that clearly in the suspenseful context of her first drone flight. You will also get a great hi-rez aerial tour of the Finike Marina and Möbius so it will be well worth a few minutes of your time. CLICK HERE and enjoy!
Another hot and busy week onboard the Good Ship Möbius here in the Finike marina as we continue to work on the seemingly endless ToDo list of jobs we need to complete to get Möbius fully ship shape to the degree that we can be confident to go to sea on her. Weather here continues to be wonderful although the daytime temps have been creeping up to the mid 30’s (mid 90’s for those who are metric challenged) but we have the AirCon working very well now and use that to cool down Christine’s office during the daytime, the SuperSalon for dinners and our Master Cabin just before we head off to bed. The “eXcessive” EPDM insulation we installed throughout the boat is really paying great dividends now as it keeps the heat out and the cooled down temps in so the loads on our AirCon chiller system are minimized.
This great weather, which is normal for us in this part of Turkey, also inspired Captain Christine to take to the air as she started to log more hours with our DJI Mavic Air 2 drone. We’ve had it for quite a while but have both been so busy with boat work that we just have not had the time to fly it and become familiar with it. Christine will put together some videos she took with it and post these a bit later for you to enjoy and I can give you this aerial view of Möbius as a teaser.
This is where we are tied up at Finike Marina and will give you a different perspective on what Möbius looks like from above. Easy to see the 14 solar panels from this viewpoint. Flying a bit further away to give you this view looking back at Möbius to help orient you as to where we are within the marina. You can Click to enlarge this or any other photo. This pano shot from a bit further out will give you a better sense of our surroundings and where we go for our evening swim after quitting work every day.
You may recall that back in June we drove up to a big hardware store north of us to pick up a new air compressor for the Workshop and after testing it out and thinking over the best location, I got around to permanently mounting it this week.
Reminding you that this is a WORK shop, so a bit messy, but you can see the white Kuletas compressor mounted underneath the Aft end of my Port/Left side workbench.
This is one of the newer types of compressors that has two motors each with two compressors so four compressors all together. This enables each one to be smaller and run at lower RPM’s and run eXtremely quietly! I can hear it come on when I’m in the workshop but it doesn’t interrupt a conversation and you can’t hear it at all outside of the workshop.
This air compressor is a super handy bit of kit to have and in addition to using it to power some pneumatic tools, clean tight passages out and blow up inflatable kayaks and the like, we use this to provide air to breathe using our Hookah or Snuba gear to work underneath or dive down to about 20m/65ft up to 100 feet around the boat.
It was definately a shoehorned fit with less than 1cm to clear at the top but this location keeps the compressor out of the way, easy to service and uses an otherwise not so usable wedge shaped space. And of course we continue to have some “infant mortality” jobs on the list such as when this seam in our brand new sand filter burst and started spraying seawater all over the Workshop.
While I hunt down a newer and better version I have just bypassed this for now and run the seawater supply to our Delfin 200L/hr watermaker through just our primary and secondary sediment filters for now. These “media” or sand filters are most commonly used for swimming pools so many of you will recognize this. However they are the secret weapon for dramatically reducing the maintenance of a watermaker by filtering out almost everything down to about 5 microns prior to going to the two sediment filters. We would normally need to clean those filters every 10 hours of use and replace them every month or so whereas with the media filter in front, the sediment filters last for over a year.
What I will do for the rest of this posting is go through the belt drive system I designed and built to power the seawater pump and Electrodyne alternator mounted on the front of Mr. Gee. I’ve been reminded by several of you that I promised to do this many months ago so my thanks for your patience in waiting until now. Hope the wait will have been worth it.
To put this all in context, I had a relatively large seawater pump and two very large alternators that I needed to mount on Mr. Gee our Gardner 6XB and then drive them both from his crankshaft.
The seawater pump weighs about 7kg/15lbs and each of the Electrodyne 250A @ 24V alternators weigh 40kg/88lbs so the mounting system needs to be eXtremely strong and solid. Both the pump and the alternator require a good bit of power to drive them so the drive system needed to be equally as tough and to be up for this task of years of trouble free service.
I won’t go into much detail on this but the seawater pump pulls seawater direct from the sea chest in the Engine Room and then pumps this water through three heat exchangers/coolers, one to cool engine oil, one to cool the engine’s water/antifreeze coolant and one to cool the Nogva gearbox oil before it finally and perhaps most importantly gets sprayed into the exhaust elbow to cool down the exhaust gas and then exit out of the boat. If this pump fails for any reason, the engine would overheat quickly and cause some extreme damage. Both of these bits of kit are therefore very critical to keeping the boat running, the seawater pump in particular so I needed to come up with a design that would be as bullet proof as possible.
There are two of these big red Electrodyne brutes which have a de-rated output of 250A @ 24V and each one weighs in at 40kg/88lbs and can take up to 20HP to drive at maximum output so their mounting and driving systems have to be equally as eXtreme.
However this essentially gives us the equivalent of a 12kW “generator” whenever Mr. Gee is running so these ensure that we never have any shortage of amps to keep our batteries fully charged and power all our electrical systems whenever we are underway.
Of course we are at anchor much more than we are underway so our 4.4kWp solar array keeps the batteries fully charged the majority of the time.
But how to mount them and drive them was the big question?
Direct PTO Mounting for Electrodyne #1
Mounting one of the #1 Electrodyne alternator was relatively easy as Gardner LXB engines have a dedicated PTO driven system for driving one alternator. I had a short jack shaft in my spare parts that I was able to machine some adaptors for that connect the end of the jack shaft to the PTO output and the input shaft of the Electrodyne. Then I was able to machine some other adaptors for these ribs where the alternator body bolts directly to the side of the Gardner crankcase. Using this Black metal band strap to hold it all together. KISS and eXtremely strong, what’s not to like?
As you can see this was quite the shoehorned fit but was relatively straightforward to do compared to coming up with a way of mounting the second Electrodyne.
Mounting Big Red #2
Physically mounting the second alternator was actually not too difficult thanks to the nice large flat mounting pad that the Gardner 6LXB’s have on their front Left corner. This was originally used to mount things such as air compressors on the automotive version of LXB’s used in trucks or to mount water pumps on the marine versions. I had another place in mind for the seawater pump so I used this mounting pad for the second Electrodyne instead. Pretty straight forward, I machined two 25mm thick AL plates and drilled them to match the spacing of the four threaded holes that were already in the mounting pad.
Then I machined and drilled the riser for the through bolt on the bottom of the Electrodyne and welded this all together. This created a super solid mounting system for this second Electrodyne. Then I fabricated a SS bar that connects to the red tab you see just in front of my knuckles here, which holds the alternator in its final position and it was now fully mounted.
But how to drive this second Electrodyne AND the sea water pump was the big question!
Mounting the Jabsco 6400 Series Sea Water Pump
Having used the Left side mounting pad on the Gardner for Big Red #2 I now needed to come up with an equally robust mount for the Jabsco seawater pump.
As you can see the pump has a simple flat mounting pad on the bottom with four bolt holes to fasten it down and wanting to KISS (Keep It Simple & Safe) I decided to go with an equally simple flat bar of 25mm thick AL which I could quite easily mount vertically over on the Right side of Mr. Gee. Didn’t take me long to fabricate this mounting bar, bolt the Jabsco pump to it and create some simple mounts for this bar to bolt onto the front right side of Mr. Gee.
As with the Electrodyne alternators, the mounting part of this puzzle was relatively easy, now on to the bigger challenge of driving both the water pump and the alternator.
Designing the Drive System
I spent a LOT of time sketching out ideas on my favorite medium; old cardboard boxes! I would sketch up very rough ideas of every possible drive system I could imagine and pulled lots of dimensions off of Mr. Gee, the Electrodyne and the Jabsco sea water pump as I refined the design. As my idea took shape I started searching for the components I would need for the actual drive components such as the pulleys for the belt and what their requirements were for power, RPM, etc.. I knew this was going to be a rubber belt drive system but traditional V-belts were just not up for the job even if I used two or three of them and they tend to slip quite easily if the belt tension is not just right and very tight. They also require very close alignment or else they start to wear and through black rubber dust all over the engine room.
Ask me how I know all this?!! For a long while I thought I was going to use a multi V serpentine belt drive setup, As per this nice lineup of different V belt types of pulleys, you can see that these multi rib belts and pulleys are able to handle much bigger loads and are more durable. These are used on millions of cars and trucks around the world to drive their alternators, water pumps, etc. so they are well proven. Better yet, I already had two of these as they came with the Electrodyne alternators I already had on hand. You can see one inside the white rectangle on the left. However, this still left me with having to custom build a multi V groove pulley to drive all this off of the front end of Mr. Gee’s crankshaft and one to mount on the keyed shaft of the Jabsco water pump. Not a big deal in and of itself, BUT if I was going to have to build custom pulleys, why not go for an even better belt drive system?
Good – Better – Best
Traditional V belt drives are good and serpentine multi groove V belts are better but cogged belts are THE best when it comes to driving high power shafts. My Harley Davidson motorcycles used these instead of chain drives so I was very familiar with them and how well they worked.
Many of you might know of these and refer to them as “timing belts” as they are used in millions of gas and diesel engines in cars, trucks, busses and boats around the world to very accurately drive the camshaft in those engines. In that job they are required to have zero “slip” or else the timing of the valves opening and closing won’t work and they need to be eXtremely long lasting as replacing them can be very expensive due to all the labour required to remove and replace them on most engines.
Once I got onto that line of thinking the choice was simple. Amongst other benefits these cogged belts gave me the following benefits:
Tried and True having been used for decades in millions if not billions of exiting engines
Readily available to buy new ones around the world if ever needed. (I of course have two spare on hand already)
Zero slip = zero belt dust = super accurate tachometer sensing on the alternator
fast, easy, tool-less belt changing
automatic tensioning with readily available spring loaded tensioners used in those millions of other engines
low axial (sideways) loads on the bearings of the alternator and water pump which in my experience is the #1 cause of failure.
Dead quiet operation; no belt squealing or squeaking
As you can see, this decision was easy, now on to designing a way to make this all work and find the cogged belt drive pulleys I would need to buy or make.
McMaster-Carr to the Rescue!
Where do you go when you have these kinds of needs for mechanical parts?? THE best source I know of, which also happens to have one of THE best designed web sites I’ve ever used; McMaster-Carr.
Within seconds, I got to this page that had eXactly what I needed. A full range of these beautifully machined cogged belt pulleys. Took me a few more hours playing around with different sizes for the three pulleys I needed to get the RPM just right for the outputs of the water pump and the alternator;
* one large 142mm pitch diameter for the main drive off the Crankshaft,
* one medium size 142mm pitch diameter to drive the Jabsco pump at its sweet spot of output when Mr. Gee is at 1400 RPM cruising speed
* and one smaller 66 Pitch diameter pulley to drive the Electrodyne at its Goldilocks RPM.
In addition to the three pulleys; I also ordered the just right sized cog belts made by Gates. Only one belt is needed but I ordered 3 so I have two for spares in the unlikely event that one belt breaks at some point. The real Pièce de résistance though came when I happened to notice down at the very bottom of the McMaster-Carr page you see up above, these “quick disconnect bushings”.
Took me a few minutes to realize just how ingenious this design was and the short story is that the smaller diameter of the quick disconnect part in my hand has a slight taper to it which fits into the matching inner hole of the cogged pulleys. This allows the Quick Connect to slide all the way inside the cogged belt pully and you’ll notice that these Quick Connects are slit on one side opposite the keyway. Holding the two parts together you tighten down the three bolts which forces the tapered QC to expand and jam itself tightly onto both the keyed shaft and the outer cogged pulley.
Brilliant! You will be forgiven for not sharing my eXcitement but for me this mounting system to attach the cogged belt pulleys to just about any size of keyed shaft was was like a gift from the mechanical gods. I quickly added three to my order and it was on its way to me.
Putting All the Puzzle Pieces Together
I now had all the pieces for this fun puzzle but still had to design it all up so that it could be installed on Mr. Gee. So I turned to my favorite 3D modeller, Autodesk’s Fusion 360 and was able to convert all my cardboard sketches into 3D models of each of the pieces and then accurately position them. McMaster-Carr provides 3D model files for everything they sell so I could quickly download the three pulleys and three Quick Connect fittings. Took a bit longer to create the 3D models for the Jabsco pump and the Gardner parts surrounding the crankshaft but with those on my screen I could then try out different positions within the constraints I had from Mr. Gee.
This was additionally challenged by the fact that I had also designed a custom version of the Gardner chain drive hand starter system which is the black line diagram you see overlaid here. Things were particularly “interesting” and close fitting down around the crankshaft where I needed to fit the red chainwheel for the hand starting chain and then come up with the Blue AL adaptor for it to spin on which in turn would be just the right spacing for the cogged belt pulley mounted on the custom Olive Green adaptor to attach the cogged pulley to the crankshaft. As you may have figured out by now I don’t throw ANYTHING away and so I had kept the original 4 V belt pulley that came with Mr. Gee, even though it had a large piece of it broken away. But this gave me the center piece that was already machined to just right fit on the keyed end of Mr. Gee’s crankshaft so I cut it out with a plasma gun and used it …. ….. to quickly machine it into this part which is the Olive Green part in the 3D model above. After making a few more parts, I could now dry assemble everything to see how well my 3D modeling transformed into the real world on the front of Mr. Gee.
Now to test how the belt fit and if all the pulley’s aligned with each other in all three planes so the belt would run true and free with no binding or chafing.
Worked out great!
BUT, there was still one critical part missing.
Can you figure out what that missing part is? Correct! I need to add in that spring loaded automatic belt tensioner!
To mount this onto the front of Mr. Gee in just the right fore/aft position so that the black idler pulley rides exactly in the center of the rubber cogged belt, I needed to space it out about 38mm so I quickly used by drill press/milling machine to build this solid AL spacer. Next I made up a template for the 10mm thick AL plate that this would mount onto. Like this. Bolted that to the Gardner cast AL support bracket supporting the cast AL cooling water holding tank, held the spring loaded tension wheel out of the way while I slid the cogged belt into lace and released the tensioner.
Et Voila! It all came together and works like a charm. Final piece of this multipart puzzle was to add in the chain drive hand crank system to make sure all the many players in this very busy front end all played nice together. You can see just how tight some of these clearances were in all this but it worked out just as I had modelled it, all the belt pulleys and chain wheels aligned with each other so they were all happy and it has been running like a charm for the past few months now.
Whew! Sure glad I was finally able to put this all together for you and for those who were brave enough and preserved to get to the end of this long and winding explanation. Congrats to all of you who did and for the smart ones who just skipped to the end.
I’ll leave you with one parting shot from Christine’s recent photo shot with the drone. It is a bit distorted with such a wide angle but this is looking across the entrance to the marina where Möbius is a bit left of center along that stone breakwater.
Thanks for joining me here again and don’t forget to add your comments and questions in the “Join the Discussion” box below.
We don’t use SCEM as filters per se, we use them to keep us on track, keep our priorities straight, by reminding us of what our fundamental values are for this boat. When doing our due diligence and research on some potential piece of equipment It is all too easy to get attracted or distracted by things like cool features or just the sheer number of choices and so as we go through our decision making we are constantly circling back through SCEM to make sure these fundamental requirements are being met.
This week in this Part 2 of our decision making process, I will do my best to summarize the more specific criteria we use to ultimately make our final decisions upon. I will cover this as a series of the following questions that we ask and answer to our satisfaction at least, as we evaluate each bit of kit and then use these to make our call.
What problem is this item attempting to solve?
Is the problem/item a want or a need?
Consequences of adding this item? Domino effect?
Does it pass the Goldilocks test?
New vs Tried & True?
What problem is this item attempting to solve?
Might sound like a silly question at first but it is surprising how often answering this question provides the most help in in our evaluation of a design decision or of a given piece of equipment. Let me use our decision of what battery type to use for our House Battery Bank to illustrate but one example of how valuable this question was.
To put this question into context, keep in mind that Möbius is a completely Battery Based Boat, meaning that ALL of our onboard electrical power comes from our House Battery Bank and therefore this is one of THE most critical systems on the boat and one that in some cases our lives can depend upon. For an XPM or any true eXpedition boat that is going to be able to carry us safely and comfortably to locations across the full spectrum of eXtremes of climate and remoteness, we need to be as self sufficient as possible and so our onboard electrical power rates right up there alongside diesel fuel and fresh (potable) water as a critical requirement. An XPM type boat is designed to spend the majority of its time at anchor or at sea, in our case often for months at a time, so in all our design and equipment decisions, we assume that we will have no shore based resources such as shore power, stores, shipping, airports, etc..
Finally, for a bit more context, let me add that we have also chosen to not have an independent generator onboard so ALL of our four voltages, 12 & 24 Volt DC and 120 & 230 Volt AC, come from our House Battery Bank. Most of the time we keep our batteries charged via our 4.48kW array of 14 320W Solar Panels and when underway we have 12-14kW available from the two eXtremely robust 250A @ 28V Electrodyne alternators which Mr. Gee keeps spinning. One of the very first decisions we needed to make to chose our batteries was what type or chemistry of batteries would be the Goldilocks just right, just for us House Batteries? I’m not going to go over this in any detail here but these are the five battery types we had to chose from:
FLA; Flooded Lead Acid
AGM: Absorbed Glass Matt
Many of you and others we talked to, thought for sure that the choice was obvious; go with Lithium and we did consider them, and all the other types, very thoroughly. But it was that question of “What problem is this trying to solve” that made it clear that Lithium was not the best choice for us and that’s the story I’d like to elaborate on here a bit.
Our battery decision making started at the very beginning of our design process, around 2016, and in some ways we designed and built the boat around the House Batteries. For the first few years, we thought we would go with GEL based OPzV batteries such as this one.
These OPxV type batteries are eXtremely robust and often referred to as “traction batteries” as they are used in things like all electric forklifts in warehouses so they had good cycle life and good resistance to sulfation and other features that wold make them a good choice for Möbius.
During this time we were reading more and more about Lithium batteries and we were seeing more and more people who were choosing to go with them so we also spent a good bit of time researching the various types and makes of Lithium, primarily LiFePO4 or Lithium Iron. This relatively new type of battery was said to have a lot of amazing features with the top ones being longer lasting (more cycle life), ability to accept much higher charging rates thus take less time to charge, but perhaps the biggest feature was their much higher energy density. This means that you get much more usable Watts from the same amount of space and weight compared to what you would get from other battery types. Said another way, you could get the same amount of energy out of a much smaller size and lighter battery bank.
As the months and years went by, these claims were validated more and more and we saw the steady increase of Lithium Iron being the batteries of choice for more and more boats so it seemed like the choice was clear right? However when we applied our criteria and use case and asked the “What problem is Lithium trying to solve?” question, we realized that we didn’t have the same “problems” as most of these other boats such as size and weight of our House Batteries.
My earlier comment that we had designed the boat around our House Battery Bank is not that far off as we had designed the hull to take maximum advantage of the characteristics of our original consideration of OPzV batteries which were very large and very heavy. Each OPzV 2/4V cell measured 215mm/8.5” Wide x 277mm/10.9” Deep x 855mm/33.6” High and weighed 110kg/242lbs each, and we needed 24 of these! As we often do, we turned this “bug” into a feature and built four large battery compartments into the framing of the bottom of the hull such that each compartment straddled the 25mm thick x 350mm high keel bar running down the centerline of the hull. By positioning these battery compartments on the very bottom and center of the hull, we effectively turned the lead in our batteries into a proxy for some of the lead ballast we needed. This is a photo from last year of one of our four battery compartments.
The point here if you are following along with me is that for the use case and design of an XPM, the “problem” that Lithium batteries would solve with their high energy density for a given weight and size just wasn’t a problem we had; we had the room and we wanted the weight. So the search for our Goldilocks batteries continued.
For awhile we continued to think that OPzV Gel batteries were the best fit for us, however, just as we had been following the developments of Lithium batteries we had also been tracking the growing use of Carbon Foam type batteries from FireFly. They ticked all the boxes on our list of criteria, most notably these were proving to be eXtremely robust and several attempts by test labs trying to purposely destroy these batteries failed and they proved to be almost indestructible which is a huge factor for us and our use case. These Carbon Foam batteries are also able to work and charge in much lower temperatures such as those we expect to have when we are in polar regions of the world and they are one of the only battery types that don’t suffer from sulfation. and are happy, even recommended, to stay at Partial State of Charge for long periods of time which would normally be the death of most other batteries.
Near the end I found real world installations of these batteries, some of which had been in place for more than ten years and so just before placing this large order of batterie we changed and ordered 24 of these 4V L15+ size Micro Carbon Foam batteries which now make up our 43.2kW House Bank (1800Ah @ 24V) made by FireFly and they have been working flawlessly for the past six months.
Let me be clear that I am NOT saying that Lithium batteries are not a great choice for many boats, nor am I saying that Carbon Foam batteries are “the best”, I am just hoping to explain how and why we made our decision to go with Carbon Foam and why they are the Goldilocks just right, just for us choice. All thanks in part to the question we regularly ask near the beginning of our decision making process; What problem is this trying to solve?
Is the problem/item a want or a need?
We often put each item we are trying to decide on into either the Need to Have or Wish/Want to Have category. Pretty self explanatory I think, Need to Have are items that we feel are mandatory must haves in order for us to feel confident in going to sea and living full time aboard Möbius. Examples for us include things like;
our high output watermaker,
Furuno Radar and other navigation equipment,
eXtremely high amounts of acoustic & audio insulation,
comfortable Helm Chairs,
that little FLIR One thermal camera I used to find the overheated wiring a few weeks ago,
great HVAC systems
Global communication capability (right now via our Iridium GO)
and items like this.
The Want/Wish to Have category can be subdivided into groups such as;
buy as soon as the budget allows
later when it is ready for real world use (ours)
nice to have, perhaps a gift to ourselves or each other
Current examples on our Wish/Want list includes things like:
second Furuno Radar with NXT technology,
forward facing sonar when it is has been in more mainstream use and is robust enough for our use case
active stabilization, most likely Magnus Effect type
kite sail with autopilot to add to our propulsion and reduce fuel usage
Portland Pudgy, Christine’s long time wish for a small, light sailing dingy
affordable high speed internet such as that being promised by 5G and satellite based systems being developed.
We also have a third category worth mentioning which is the Don’t Want Onboard category which is sometimes the best choice. Items on this list would include things like;
anything that requires propane (too much of a pain to fill around the world)
anything that requires gasoline (too short a shelf life these days)
Consequences of adding this item?
As a good friend and fellow world sailor likes to say “Everything needs” and so we spend time trying to imagine what the needs and other consequences will be if we add this bit of kit to Möbius. Our primary prioritization of Maintenance, lack thereof, would factor into this for example and hence decisions such as;
no paint/wood/SS on the exterior,
being single fuel boat with no propane or gasoline,
but it could also be other consequences of adding this item to our boat. An XPM is complex by virtue of needing to be so self contained and as we often say Möbius is like a floating village in that we have to look after making all our own water, all our own energy, dealing with all our own waste and so on, but we do strive to apply the KISS or Keep It Simple & Safe philosophy to all our decisions by finding the simplest solution possible. Examples of this would include:
manual roll attenuation with our fully mechanical/manual Paravane A-Frames
manual Tender Davit system vs hydraulic
Gardner engine (no turbo, no electrics, low revs, etc.)
The Domino Effect is perhaps a branch of the consideration of the Consequences of any decision as I just outlined above and is when the result of a decision has follow on effects to other systems on that boat. This can work both ways; sometimes these dominos are positive ones and in other cases they are negative or undesirable consequences. For example, installing the eXtreme amount of EPDM and acoustic insulation throughout the boat has a domino effect;
stabilizes the interior temperatures and makes them more temperate in both very hot and very cold climates
this reduces the energy required to cool/heat the boat
this allows us to install smaller capacity and less expensive HVAC systems such as Air Conditioning and heating
this lowers the demand on our House Batteries and HVAC systems so they run with less loads and last longer
An example of when the Domino Effect can work the opposite direction might be the option we considered of installing fin type active stabilizers. These work extremely well to reduce the roll in many conditions when on passages but they would also introduce a Domino Effect of consequences that took them out of the running for us, such as;
their protrusion from the side of the hull reduces the safety factor when in areas with uncharted rocks, coral heads and the inevitable groundings on these.
not suitable when ice is present in polar waters
unlikely but possible if a fin is hit hard enough to create an underwater breach of the hull
are extremely complex and often top the lists of most maintenance problems we read from other global passage makers.
most require a significant hydraulic system to operate which adds yet another whole system onboard to maintain and repair.
I might add that having gone through this Domino Effect as we considered active fin stabilization, it also helped us see that we could find a different type of active stabilization if we should ever want that, and one that eliminates most of the dominos I listed above. This would be stabilizers that use the Magnus Effect which is offered by several different manufacturers now.
Does it pass the Goldilocks test?
We essentially answer this question by virtue of having gone through all the questions and priorities I’ve already listed. Because we have highly personalized our overarching principles of SCEM and articulated much more detailed specifics of our use case, our decision making helps us ensure that we are making choices and decisions that are by definition, Goldilocks, just right, just for us.
However, this is such an important factor for us that we do keep coming back to to this “Goldilocks Test” to make sure we are avoiding the tendency to “go with the flow” of following what others are doing or “the way its always been done” and are staying true to ourselves and our preferences. I will site a more “meta” example here which is our decision in the design phase to “upsize” the length of the boat from the 18-20m / 60-65 ft that we initially imagined and then at the same time “downsize” the interior to have just 2 cabins and 2 heads.
Our decision to extend the length to 24m/78ft was driven two factors; simple physics that hull speed is a factor of Length on the Waterline and our discovery that contrary to popular opinion there is not very many restrictions on boats that are over 20 meters whereas there are some very significant changes to the rules governing ships that are over 24 meters. With our prioritization of efficiency, we pushed the length to just under 24 meters. With our infrequent use of marinas the increased docking fees do not affect us very much. Furthermore, with more and more catamarans being purchased, many marinas are changing their dock rates to be calculated based on overall area of each boat, LOA x Beam and so our slender 5m Beam reduces our overall area and we are often cheaper or about the same as much shorter but wider boats.
Our decisions to “downsize” the interior and thus reduce maintenance and costs was based on the fact that 99% of the time Christine and I are the only two people living onboard so we wanted to make the interior fit us and our needs. Our Master Cabin is very spacious and luxurious for us. Our Guest Cabin works very well when we do have guests onboard but most of the time it is a very purposefully designed Office for Christine Kling, the Captain’s nom de plume when she is working on her next book and running her growing book business. Our SuperSalon is indeed living up to that name the more we live in it. And my very full size Workshop and Engine Room is that of my dreams.
There are many other examples of how the Goldilocks Test has driven our decisions such as;
Manual Paravane system and Tender Davit that is KISS and as former sailors handling lines, winches and clutches is second hand.
Though we designed and built the cabinets, electrical and plumbing for them, we chose not to install either a Dryer or a Dishwasher as we are just not fans of either one and prefer washing and drying by hand.
I could give countless more examples of how we have applied the Goldilocks Test to almost every decision we have made during the design and the building process but I think you get the idea. We have now been living aboard Möbius since she first launched in February and we are finding that our continuous use of this Goldilocks Test has worked eXtremely well for us in designing and building Möbius and we can and do recommend it highly for almost all decisions and choices you make.
New vs Tried & True?
Christine and I are self described nerds and geeks so we have a great fondness for technology that is on that well named “bleeding edge” and we have a full compliment of devices to show for it. However, when it comes to equipment for Möbius, and especially all of it that is on that Must Have list, it must be remembered all those decisions must be made within the context that Möbius is an XPM type boat that is designed and built to live up to that acronym for eXtreme eXploration Passage Maker. So when it comes to deciding on equipment, materials, construction and design of these items, they must, all be Tried & True. To us this means equipment that has been in regular use on boats, ideally with similar use cases as ours, for several years and has stood that test of time.
Some examples of this for us include:
we delayed our decision to go with FireFly Carbon Foam batteries until after we had been able to find enough examples of these batteries being installed in other people’s boats in large numbers for many years.
We chose to go with all Furuno for navigation because it is so widely used by commercial boats in fishing fleets, government agencies and the like and hence this equipment is designed and built for continuous 24/7 use in some eXtremely harsh conditions. They also have an excellent reputation for their continued support of even their oldest equipment.
Our decision to go with a Gardner 6LXB engine that is still one of the most efficient diesel engines ever produced and is still in use in thousands of commercial boats worldwide. It is also perhaps one of the best examples of the KISS approach to design and engineering which adds to how well it passes the Tried & True test.
individual MPPT controllers for each of our 14 solar panels as this has been well proven to be the most efficient combination for both overall efficiency, least affected by shading and highest redundancy.
Let me end with a final example of the value of taking this Tried & True test for mission critical ships and equipment from no less than the US Navy! A recent article caught my eye a few weeks ago where even the us Navy has learned the folly of installing untested equipment on their ships. This link to the article USS Gerald R. Ford Problems: The Navy Admits Its Big Mistake (popularmechanics.com) provides a brief but telling story. as outlined in that article the Chief of Naval Operations, Mike Gilday, says the U.S. Navy built the aircraft carrier USS Ford with too many new technologies. such that now, the Ford is several years behind in its life cycle because of problems with many of those new technologies.
The last of the Ford’s four advanced weapon elevators, the most glaring example of the ship’s tech gone wrong, should enter service later this year.
When the Navy first built the Ford, it incorporated nearly two dozen new technologies, some of which are still giving the service headaches 4 years after the ship entered the fleet. Those delays meant the Navy only commissioned the Ford in 2017, despite laying it down in 2009. Even then, problems lingered, especially with the electromagnetic aircraft launch system (EMALS) and the advanced weapon elevators (AWEs).
The ship’s first full deployment, originally scheduled for 2018, is now set for 2022.
I think this unfortunate real world example does help to make the point that for XPM types of boats with use cases to match, all the “mission critical” equipment onboard MUST have passed the Tried & True test.
Bubble Bubble, Toil & Trouble!
Leaving you with the latest bit of kit that Captain Christine just approved and installed onboard, a fully manual sparkling water maker! Especially in these hot summer months, Christine particularly enjoys her cold sparkling water and I do too but we don’t like having to buy it in cases of plastic bottles. We have our watermaker for similar reasons for our regular drinking water. Initial tests have elicited the same smile you see here so this item has now passed the all important Captain’s Test and has been welcomed aboard. Thanks so much for making it this far if you have and I do hope that this slightly different format and content is of interest and value to most of you. Let me know either way with your comments in the “Join the Discussion” box below and I’ll be back with more for you same time next week.