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.
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.
As most of you know by now, Christine is American and I am Canadian so this was a big week as both our countries celebrated their independence within days of each other; Canada day on Thursday July 1st and today being July 4th for the USA. However, Friday July 2nd, was THE most special independence day celebration for us as this was the day we felt we and our new world aboard Möbius achieved our true independence. Why Friday? Well because that was the day that we took Möbius out for her maiden voyage and a whole set of firsts such as our first overnight on anchor. Hard to capture how this felt having been five years in the making but I’ll do my best, try to keep it short and let the photos do most of the talking with that “photo is worth a thousand words” thought in mind. Here goes ………
After waiting SO long for this to all happen the past few days have been a bit of a blur and reminds me of the “hurry up and wait” condition I learned in the Canadian military.
Mid day on Monday Christine went up to the marina office to let them know that we would be ready to launch in the next few days and they told her that the TraveLift was going in for service tomorrow so if we wanted to launch it had to be NOW! Fortunately I had Mr. Gee all back together again and running the day before which was where I left off in last week’s update posting and the remaining jobs could be done in the water so we were good to Go! This is actually the third time we have splashed Möbius here at Setur marina so it didn’t take them long to get the slings positioned under Möbius round belly and we had lift off in no time flat. Down came all the vertical posts holding us up and we were headed for the TraveLift launch pads. Which are less than 100 meters away so again, mere minutes. We hover over the water for a few minutes and then down we go till the straps are loose and I can head below to check for any leaks. All’s well down below, just the way we like it, not a drop of salt water to be found and so we give the thumbs up to the crew with our thanks and the TraveLift is off for its servicing leaving us floating merrily in the water at last.
Flange Alignment v2.0
One of the last jobs of putting Mr. Gee all back together again was to recheck the alignment of the flanges that couple the output of the Nogva CPP gearbox to the prop shaft.
If you have been following the whole Mr. Gee v2.0 rebuild you may recall that I left the Nogva gearbox bolted in place to the engine beds with the two anti-vibration mounts on either side so it *should* not have moved but this alignment is critical to smooth vibration free power transfer from Mr. Gee through to the 1 meter OD 4 bladed CPP propeller and as per the illustration above, the two flanges have to be near perfectly aligned with no more than 0.05 of a millimeter deviation. For reference a strand of average human hair has a diameter between 0.06 and 0.08 mm.
Not a difficult job, fist step is to remove the composite grated flooring and unbolt the sealed AL panel underneath to reveal the space where the prop shaft enters the boat. Then remove all 8 hardened bolts around the flanges, pull the flanges apart by sliding the prop shaft back a few inches and then moving it forward till the two flanges touch. Then you use feeler gauges to determine the exact size of any gap between the two flanges. In my case the gap was 0.06mm so it only required a tweak with a pry bar on the front of the Gardner to eliminate that and then I could torque the 8 bolts back to a grunt worthy 240 Newton Meters and the propulsion system was good to Go! It was also time to say bye bye to Mr. Gee’s original crankshaft and pack him all up for a safe trip back to Gardner Marine Diesel in Canterbury England where they will grind all the journals and have it ready to be installed in the next marine 6LXB engine they build.
At about 220kg / 485 Lbs, the wooden crate that GMD had made to send the new crank to me, would work well for the return flights and I added a few 2×2 timbers through screwed into the framing of their crate for good measure and one more component is Good to Go!
SkyBridge Lounge Act v1.0
As we are doing with many aspects of this very new boat, we are using this first year of living aboard to make lots of adjustments as we determine just how we tend to use various spaces and equipment and THEN we will build them in permanently. The most recent example is the layout and furniture for the upper SkyBridge area in front of the Helm Station.
What we decided to do is buy some inexpensive modular outdoor patio furniture which we could rearrange into various different configurations to see what we tended to gravitate to and use most often. Once we know that I can build in a more permanent set of furniture next year.
So Captain Christine has been on the hunt for the past few months at all the home supply stores here in Antalya and her choice arrived on this pallet on Wednesday. The L-shaped sectional couch and glass topped table are made from aluminium tube covered with plastic rattan like weaving so they are super lightweight and will work well in our salty environment.
Minutes later, the Captain could take the new lounge setup out for a quick test drive and seems to be pleased with her choices. I soon followed suit and am sitting here now typing up this blog post for you. Not a bad office, and one of several we no have onboard.
Wayne’s Newest Toy!
Christine and I are both running on fumes energy wise and so on Thursday we took the day off to drive about 2hrs north to the big city of Denizli where a brand new air compressor was waiting to be picked up. I had sent a new compressor over from Florida with all our other effects and boat parts a few years ago but it was DOA due to a faulty install and the best option for this critical bit of kit was to go for an upgraded new version which you see here on the Swim Platform Thursday afternoon.
2HP dual motors with dual compressors on each, 60L AL tank and super quiet!
I will soon be mounting this compressor under one of the AL workbenches in the Workshop where I will plumb it into the PVC pipes that run the full length of the Port side of the hull all the way up to the Forepeak with quick connect fittings in each area along the way. I’ve had compressed air on boats for so long I can’t imagine a boat without and use it daily for powering pneumatic tools such as sanders and impact guns and being able to clear out debris from clogged tubes and just general cleanup. Also super handy for quickly filling things like air mattresses and our inflatable kayak.
Compressed air is also how I clear any clogs in our Sea Chest with a quick blast in the fittings installed in each plexiglass lid.
But perhaps our favorite use is to supply the air for our two Hookah regulators which allow us to stay underwater with just a regulator in our mouth, no tanks, to do maintenance on the hull such as keeping the silicone foul release paint super slick and clean or to explore some of the nearby coral and underwater life around Möbius. We will also have a 12V Hookah setup in the Tender to be able to enjoy underwater wonders further afield.
Maiden Voyage v1.0
Still not quite believing it, we seemed to finally be ready to head out to open ocean waters for the first time and have Mr. Gee take Möbius and us out for our Maiden Voyage! With everything from Mr. Gee to so many other systems being all new or on version 2.0, we spent Friday morning checking everything over multiple times, getting Mr. Gee warmed up, bow thrusters working, steering working, charting and all nav systems working and at 13:20 Friday July 2nd, 2021 we cast off the dock lines and headed out through the breakwater of the Antalya harbour to officially begin our latest adventure.
In a rare attempt at brevity to try to say how pleased we are, I will simply show you a set of shots of the wake we left as we slowly increased the pitch and thus speed through the water as we pointed Möbius’ bow to the horizon. These shots of the wake behind Möbius at different speeds probably won’t be too exciting for many of you but for us, this is a huge part of the “proof of the pudding” from all the time we invested with Dennis in designing this hull to be eXtremely efficient for maximum speed with minimum power and fuel burn and to be slick, slippery and smooth as she slices through the water.
This is the wake at 7.2 kts off the Swim Platform. Longer range shot still at 7.2 kts 20 minutes later, dialing in a bit more pitch this is what it looked like at 8.5 kts Just a bit more speed with a bit more pitch but still keeping well under full load as we break in Mr. Gee very gently, this was our top speed for this first outing of 9.2 kts. I will publish tables of data like this in the coming weeks but one quick shot for those curious, this is the EGT and Fuel burn rate at 8.5 kts with Mr. Gee spinning at 1500 RPM. For reference, EGT at full continuous load rating for Mr. Gee at 1650 is 400C
After two hours testing out different pitch/speed combinations, some hard turns and circles to familiarize ourselves with steering and handling Captain Christine headed us for this small nearby uninhabited island. At her cue I dropped “Rocky” our 110Kg / 243 Lb Rocna anchor into the sea for his first bite of bottom sand. As usual for a Rocna he bit right away in about 30 feet of water, Christine backed down to give him a good pull for a few minutes and Möbius settled back with the 13mm / 1/2” chain hanging straight down in these calm waters. First order of business?
Our first dives off the Swim Platform!
(you can just make out Christine about to enjoy her first dive into these cool clear blue Aegean waters.) We swam around Möbius for the very fist time under Barney’s close scrutiny from deck. While this view of the shoreline of the mainland off our Port side isn’t too bad, what was breathtaking for us as we did our first lap around Möbius, was to be looking up to see our visions we developed over all these past years now be a realty looming overhead.
Suffice it to say that our fist night at anchor was pure bliss!
Oh, and for those curious, Mr. Gee performed flawlessly throughout the 5.5 hours we ran him out and back on this Maiden Voyage. Here is a shot of his oil pressure and oil temperature after running at various loads for about 2 hours on the way back to the marina on Saturday doing about 8.5 kts @ 1500 RPM. As happy as you can imagine we were when we returned to the marina yesterday afternoon after about 3 hours of more testing and maneuvering, we are even MORE excited here on Sunday night as we fly to Istanbul in the morning to meet our daughter Lia, husband Brian and our two granddaughters Brynn and Blair! This is a family get together that has been delayed for over 2 years and we are eXtremely eXcited to see this vision also become reality and I’ll have a bit more about this in next week’s post when we fly back here with all of them next Thursday.
Thanks for joining us through this eXtremely long and winding adventure that it has taken us to get here. Hope you have enjoyed it and we will continue to keep you posted as we switch into cruising mode and can provide more of the real world data and experiences aboard XPM78-01 Möbius that many of you are apparently anxious to receive.
Whew, I am one pooped pirate! Partly because like many of you apparently, we have had an eXtremely HOT week here in Antalya weather wise with daily highs around 40C/104F and we hit 42C/108F yesterday during the day and only dropped down to about 30C/86F for the evening so its been a bit toasty. And as “luck” would have it, being out of the water right now we can’t run our AirCon system as it requires seawater for its cooling pump.
Things have also been smokin’ hot progress wise this week as the GA1 aka Gardner Army of One aka yours truly continues to put in very full days getting Mr. Gee, our beloved Gardner 6LXB main (and only) engine, all back together again, running and soon thereafter ………………… splashing back into the water!
Captain Christine and I are now affectionately referring to him as Mr. Gee 2.0 which seems appropriate as he really has been “born again” as this is his 2nd full renovation after the first one I did last year after we acquired Mr. Gee from a tugboat on the Thames River in England. As all you regular readers know from following along on this adventure (Thanks!!), we had a disheartening debacle during the first few minutes of the first sea trial when the CPP Pitch lever was pushed fully forward to maximum pitch which put an eXtremely large and sustained overload condition rather than the gradual breaking in of this brand new engine that the hired captain had been asked to do.
As all you faithful followers now know, this required that we lift Mr. Gee up about 1 meter above his comfy Engine Room bed to allow me to do a second full tear down in order to replace the crankshaft, bearings, rings, etc. with all new parts and get Mr. Gee back to his next new life. Hence version 2.0 which should last us for many decades to come which is the norm for these eXtremely strong and simple Gardner engines.
So I will pick up where I left off last week, with the last of the reassembly process, lowering Mr. Gee back down onto his Engine Beds and hopefully getting him running again, adjusted and ready to go back where he and we belong; in the water!
Ready? Got a comfy chair in a cool spot with a cool beverage? Great, let’s jump right in……………
Even the Turkish Polish Approve!
Mid morning on Monday (June 21, 2021) as I was working away on Mr. Gee in the Engine Room, I heard a knock on the hull and a voice calling to me. You can picture my face as I emerged to find five fully uniformed Turkish Marine Police standing on the Swim Platform and peeking through the door into the Workshop! What else would a Canadian say but “Hi, can I help you and would you like to come in?
We had seen the TraveLift pull up in front of us with this relatively new Police Patrol boat as this was where the marina staff do all the pressure washing of vessels that get hauled out so we didn’t think anything more of it.
Turns out that they had seen Möbius for some time and had been quite intrigued by this very unusual almost military looking boat and wanted to know all about it.
Turns out that they are in the process of designing their next new boat and the Captain on the far Left in the photo below, was very taken with the design and features of Möbius and wanted to know much more about it.
The Officer in the middle here spoke quite a bit of English so he did all the translations for the others and they spent about an hour with us asking more and more questions. As usual Barney was an instant hit and spent the whole time being held and well attended to by all the officers as they spent about an hour onboard with us until their boat was ready to go back into the water and they had to leave.
Now THAT is the way to be boarded by the marine Police!
Making Mr. Gee 2.0 Better Yet
When I do repairs on boats I always try to do more than “just” fix the problem and do some things which will make the boat better than before and so I took a bit of time to give some of Mr. Gee’s parts a fresh new coat of tough epoxy paint.
I set up this temporary workbench outside with my trusty grinder and wire wheel to clean up parts such as these main bearing cap cross bolts, nuts and washers. I also decided to change a few of these external parts to a contrasting glossy Black rather then the previous Burgundy color to make Mr. Gee even classier than he already was. Oil Filter housing and cap on the Left then Fuel Lift Pump, Oil Heat Exchanger Pump, and Oil Pressure relief valve on the far Right. The kind, wise and beautiful Captain decided to treat me to a bit of a “makeover” as well by having her print shop buddy she had gotten to know over the past 3 years, to print and bind the Gardner parts and technical manuals that I rely on SO much every day. I only had the one on the far Left previously printed a few years ago but had since acquired several even better ones and a full parts manual (top middle) and so it was a wonderful surprise when the printer dropped them off with his son as they too wanted to get a tour of Möbius.
Back On His Feet Again!
When we left off last week, I had the new crankshaft in place along with all its attached bearings, connecting rods, pistons, rings, etc. and had bolted up the massive cast AL oil sump to the bottom so Mr. Gee was now ready to be reunited with his buddy “Normy” the Nogva CPP or Controllable Pitch Propeller gear box.
This required lowering Mr. Gee from his lofty position you see here, and he also needed to move aft about 25cm/1 ft so that their two mating SAE housing surfaces lined up precisely.
I called for the expert, Captain Christine ** to run the front chain block while I managed the aft end where hidden from view inside the AL housing on the bottom here is the CentaMax flexible coupling. ** Note the Captain’s hair here. You’ll understand why at the end.
The massive torque Mr. Gee puts out gets smoothly transferred to the Nogva CPP via this CentaMax 1600 SAE14 flexible drive system which makes it relatively easy to line up all those aluminium “fingers” with their mating U shaped grooves in the thick rubber disk that is bolted to the input shaft of the Nogva gearbox. I had rigged up two chain hoists for just this reason as it made it easy to adjust the angle as we lowered Mr. Gee in place and put him back on his Feet again where he attaches to the 25mm/1” thick AL engine beds on either side.
Click to enlarge and immediately above that Blue masking tape patch, you can see the outer AL portion of the CentaMax drive that is bolted to the Gardner’s flywheel sitting in between the Burgundy Nogva SAE 14 housing and the matching Gardner flywheel housing. Going in stages down and aft and wiggling the suspended Mr. Gee, it was quite easy to get the two halves of the CentaMax drive system lined up and slid together.
Lined up perfectly here and just the last centimeter to go. That last cm is a bit trickier as these two housings had to line up precisely to allow the sliding fit of the hardened bolts to go through their holes on the Noga and thread into the holes on the Gardner’s AL housing. But didn’t take too much “wiggling” to get them lined up and you can see the bolts now in place here so Mr. Gee and Normy are solid once again!
Putting Humpty Dumpty Together Again
Now it was largely a matter of putting all of the removed parts back onto Mr. Gee which is quite straightforward but does take time as you have to fit all new gaskets and seals, adjust things like valve clearances, injection timing and so on. Having already done this once before helped it go very smoothly and the new manuals and sage advise via WhatsApp text messages from my Gardner expert and counsellor, Michael Harrison at Gardner Marine Diesel in Canterbury England who is always ready to provide me with invaluable assistance.
Thanks Michael and all your crew at GMD.
Shiny Black Oil Filter housing with original Gardner Brass Oil Temp thermometer in the bottom Right and I’m also now installing all the copper external oil tubes and fuel lines.
While I was at it, I freshened up the Gardner logos with matching Black paint background and repolished the raised logos on the six access ports on the upper sides of the cylinder heads. These covers are now bolted on and take their place along with the three matching Gardner logos I have also freshened up on the Fuel Injection Pump assembly below. A bit closer look at where the oil tube attaches to the bronze manifold on the side of the Oil Filter housing below the Oil Pressure gauge and carries fresh pressurized oil into galleries cast into the cylinder heads which pump oil into each of the valve rocker arms to keep them well lubricated and smoothly running for decades to come.
Hand Crank Starting System!
This is perhaps Captain Christine’s favorite features of Mr. Gee, his hand crank starter! Yes, you read that right and No I am not kidding, should our starter or batteries fail it is no problem to start Mr. Gee by hand cranking him!
Top chainwheel is connected to a long shaft that runs all the way to the handle on the aft end and then the chain goes down around the Black chainwheel at the very bottom here which is attached to the crankshaft. Careful observers will also note the AL idler chainwheel in the bottom Right corner that keeps the tension on the chain just right. Here is the long drive shaft I mentioned above, making its way to the very back of the engine where the hand crank attaches.
While the hand crank was a standard Gardner option, they had changed to put the crank handle on the front of the 6LXB models and so I had to do quite a bit of tricky engineering using Gardner parts from the old and new models along with some that I machined myself to keep the hand crank at the rear as there is no room to do this at the front on Möbius. As you can see here the fit is just a wee bit close!
But it works like a charm and I use this hand crank almost every day when I need to rotate the crank to a new position for doing valve or injection timing and things like that.
I will do a little video of hand starting Mr. Gee in the next few weeks for you non-believers!
Cogged Belt Drive Alternator & SW Pump
As tricky as the hybrid old/new hand crank system was, the true test was this cogged belt drive system I designed and built for Mr. Gee to power one of the two monster Electrodyne 250Ah @ 28V alternators (the 2nd one is powered by the built in Gardner PTO) and the bronze sea water pump that circulates cool seawater through all the heat exchangers and the wet exhaust system.
You can see the 3 special pulleys for the cogged belt’s “cogs” to run in and many of you would know these systems as serpentine belts or timing belts which drive the camshafts in most modern engines both gas and diesel for the past 30+ years. Super long lasting with zero slippage and able to drive large loads with no belt wear or stretching. Easy to see how this works when I fit the cogged belt loosely in place around all three pulleys.
I won’t bore you with all that it took to design, build and mount this this cogged belt system, at least not now, trust me when I say that this eXtremely unique to Möbius setup was a very fun challenge and I’m delighted with how well it all worked out.
One of the reasons why these belt systems are so widely used and so long lasting is that they also require zero maintenance or adjusting. This is partly achieved by the special Kevlar reinforced cogged belts, and I chose ones by Gates as they are the most commonly available worldwide. But the real trick to long, maintenance free life is that they use a heavy spring loaded belt tensioner to keep the tension always the same Goldilocks just right amount.
So I ordered a Gates tensioner pulley that is used on Toyota and many many other brands, again for worldwide parts availability, and them built the AL plate to mount it on that you see bolted to the Gardner AL A-frame for the Hand Crank chainwheel up on top. It was difficult to film single handed but to install the belt in the photo above, I just pull the spring loaded Black pulley up and slide the belt underneath.
Est voilà c’est tout!!
As timing belts in cars and trucks, these belt systems last for 100-150,00 miles of use under much more stress and strain so this setup should outlast me and Mr. Gee!
However, should this belt ever fail, there is a spare new one mounted above and as you have seen here it would take mere seconds and NO tools, to install a new one in an emergency at sea.
Fuel Injection System
The final and perhaps most important system to install is the Fuel Injection Pump, pipework’s and Injectors.
The Injection Pump that creates the eXtremely high pressure that forces the diesel fuel to atomise as it exits the tiny little holes in the tips of the injectors, is seen here with the 6 vertical Black “priming” levers. This is one of the 6 injectors and as is the norm with Gardners, these are all mechanical and super simple. No moving parts inside just eXtremely precisely machined parts to ensure a smooth travel of the high pressure diesel from the pump down the the 3 holes in the bottom of the injector nozzle. One of the features of a Gardner that I SO appreciate is that they designed and built them with servicing and service people in mind. What a concept!
In this case, I wanted to test each injector to make doubly sure they were all working and putting out the same injector pattern. Need to take to a Gardner testing shop? Nope!!
Just rotate the fuel pipe that connects the Fuel Injection Pump to the Injector body so it is outside the engine, tighten the injector to the pipe and then give the Priming Lever a few sharp hard pulls while you watch the spray pattern coming out of the 3 holes in the nozzle.
KISS at its best! Smart, Simple, Safe! All 6 injectors had the exact same spray pattern and so they were ready to drop gently in place into the cylinder heads and toque down the simple lever arm that holds the tapered end of the injector body against the matching face inside the head. No gaskets or seals requires, simple metal to metal tapered seat sealing.
I finally treated myself to a 1/4” drive torque wrench and this was its first use to torque down the 6 fuel injector body clamps just right. The threaded hold down “nuts” are castellated rather than hex head so I made up this special tool to fit and enable me to use the torque wrench to tighten them precisely. Used and old socket and my handy dandy Dremel tool to cut away these 4 teeth to fit the slots in the nuts. Together with my lovely new 1/4” torque wrench this worked like a charm and the injectors were quickly torqued down to factory specs and I could finish tightening up all the Black pipes to each injector and the return ones which take the unused fuel back to the tank. All the fuel injection pipes in place and torqued to the Injection Pump Body. Fuel injection system installed, tested and ready for service Captain Christine!
About all that’s left now before starting Mr. Gee up is to pour in the 28 liters of oil and 24 liters of water (to be replaced with antifreeze when fully tested for leaks and such) which is what I did just before starting to write up this blog post. So I will leave you here for now.
What’s that you say?
How dare I leave you hanging like this?
What more could you possibly want???
Oh, you wanted to know if Mr. Gee started??!?!?!?
Well, OK then, seeing as how you have been such patient boys and girls throughout Mr. Gee’s version 2.0 rebuild ………………..
LOVE that sound! Truly music to our ears!
We only ran Mr. Gee for a few minutes today because we are on the hard and have no seawater source.
I’ll have more testing and updates for you next week but as you have just seen, Mr. Gee 2.0 is ALIVE! and running once again!
I know all of Mr. Gee’s loyal fan base will be disappointed but this is likely the second to last episode in the Low Oil Pressure Season of As Mr. Gee Turns. Have no fear however as I am already cueing up the next Season where Mr. Gee will be living up to the series title as he turns his crankshaft round and round with ease to similarly powers Möbius’ CPP propeller to spin as we go round and round this awemazing world of ours.
Those of you who are waiting on the edge of your seats for the final outcome of this season’s mystery thriller to find out who it is that is finally found guilty of murdering poor Mr. Gee will be glad to know that the jury is finally back with its definitive verdict! The title of this week’s update will give you a clue but you’ll have to read on to find out who turned out to be the dastardly killer on that ill fated maiden sea trial.
With that baited opening, let’s jump right in and pick up where we left off last week.
Circumstantial Evidence is Suspect for Good Reason!
In typical TV Series fashion, here is a quick summary of “as seen in previous episodes” …………
All of you who have been following along so closely (thanks!) will recall that from the very beginning the prime suspect in this murder mystery has been “Nick”, this mysterious dent in the steel oil pipe inside the crankshaft that carries the vital pressurized oil from the main bearings up to the connecting rod bearings.
It will likely remain a mystery as to what/how/who could have inflicted this dent in the oil pipe to begin with but the suspicion has been that Nick created a hole or a thin crack in the oil pipe at cylinder #1 and when Mr. Gee got up to operating temperature and loads, the oil sprayed out of the oil tube causing the deadly loss of oil pressure and the subsequent destruction of the main and connecting rod bearings. When I did the first full factory level rebuild of Mr. Gee las year and found Nick hiding in the recess of the lightening hole at Cylinder #1 my conclusion after doing some preliminary testing was that it was “just” a nick and that the walls of the oil pipe had not been breached and did not leak. However, after the sudden loss of oil pressure during the first sea trial and the subsequent discovery upon tearing down Mr. Gee of this catastrophic failure of the main and connecting rod bearings you can see here, all the evidence pointed to me having been wrong about the oil tube and I immediately gave myself a good kick in the a$$ and pleaded guilty of letting Mr. Gee and the whole Gardner engine family down by not living up to the highest level of Gardner standards for 100% confidence inspiring quality of workmanship.
In that first rebuild, I took what I thought at the time was more than enough of a “belt & suspenders” approach when I silver soldered Nick for an extra measure of security just in case there was a hole or a crack in the oil tube. However, as the evidence accumulated as I stripped poor Mr. Gee naked, it all pointed to ME having screwed up by not replacing the crankshaft of at least replacing the oil tube with a new one.
Circumstantial Evidence Just Won’t Do
When I removed the crankshaft and was able to inspect it even more carefully, it still did not appear that there was any hole or crack in the oil tube BUT this time I was going to leave nothing to chance and so I had a whole new crankshaft along with a lot of other parts, gaskets, filters, etc. shipped from Gardner Marine Diesel in Canterbury England and they all arrived just in time last week.
However, I was just not going to be able to SWAN or Sleep Well At Night just putting Humpty Dumpty aka Mr. Gee back together again with just all this circumstantial evidence. I had to know for sure what had caused the oil pressure to drop and the bearings to fail.
So I came up with a way to test the suspected oil tube and prove once and for all if it was the guilty party or not?
First, I threaded one end of the oil tube and screwed in a SS set screw coated with sealing compound. Next, I taped the other end of the oil tube where it exited out of the main bearing journal with an M6 thread. This kind of rigorous laboratory testing does not come cheap and unfortunately two innocent bicycle tubes paid the ultimate price and gave their lives to the cause. They contributed these two valve stems, which were the key to this test by allowing me to pressurize the oil tube to a known level and keep it there. I carry a full set of Imperial, Metric, British Standard and Whitworth taps and dies (the tools that cut male/female threads in metal) and so I quickly cut some M6 threads on the valve stem I liked the most. And screwed it into the open end of the oil tube which I had previously tapped above with matching M6 threads.
I removed the valve from the stem and poured 10W40 engine oil to fill up the oil tube and put the valve back in. Out came my trusty hand pump which also has a gauge at its base and I pumped it up to about 120PSI, which is more than three times the normal 38 PSI oil pressure of a Gardner 6LXB. I had my hands full so didn’t get any photos, but I then used my industrial heat gun to heat up the oil tube and the surrounding area of the crankshaft to about 70C / 160F which is higher than the normal operating temperature of oil in a 6LXB which is about 60C. Having replicated all the conditions the oil tube would have been under when Mr. Gee was spinning away on that fateful day, this test would tell me once and for all if there was the least bit of leakage of oil from this oil tube.
Prior to testing, I had scrubbed the whole area around the oil tube surgically clean so even a drop of oil would be easy to see. It was with very mixed emotions that after repeated tests, not a single drop or dribble of oil emerged!
Nice to be vindicated and have proved that either the dent or Nick had not penetrated the walls of the tube and/or my silver solder patch had done the job.
Nick was immediately released from custody with the sincere apologies of this kangaroo court, but I was now left back where I started, not knowing what the source of the problem was!
So I did what you do in such situations, you“go to the mattresses” and call in the experts. In this case I reached out to my two best experts in such areas; Michael Harrison who is “Mr. Gardner” and owns/runs Gardner Marine in Canterbury and Greg, one of my longest running best friends from back in the days when we were both working nights and weekends as heavy duty mechanics at a large lumber trucking company in Vancouver BC while we were both going to a combination of UBC the University of British Columbia and BCIT the British Columbia Institute of Technology, to become Industrial Education teachers aka “Shop Teachers”.
I had been in touch with Michael and Greg since the low oil pressure fiasco had begun and was sharing lots of photos online and daily updates as I worked on Mr. Gee. Michael, who has worked on hundreds of Gardner powered boats all over the world, came up with the key when he posited that we/me were thinking about this backwards. It was not that the wear on the bearings was caused by low oil pressure, it was the other way around! The low oil pressure was CAUSED BY the wearing of the bearing material which allowed more and more oil to escape out the growing space as the bearing material wore away.
OK you might ask, but then what caused the wear in the fist place?!?!?!
If you really want to know the answer to this question, please keep reading but there are no photos to go with this so it will just be my text based explanation to walk you through it. You will be fully forgiven if you want to skip down to where we resume our normal photo based programming!
After walking through the events more thoroughly and with Michael’s vast experience with Gardner engines and Greg’s decades of experience with diesel truck engines of all kinds and then my notes and recollection of the events leading up to the failure, we were able to figure out the TWO contributing factors that caused to the rapid wearing of the bearings and the subsequent loss of oil pressure.
Factor #1 is that I had reused Mr. Gee’s original crankshaft “as is”. That is to say I did not replace it or send it out to have all the journal surfaces reground.
I have rebuilt a LOT of engines over the past 50 years and what you/I normally do is completely inspect the crankshaft of the engine you are rebuilding. You use very accurate micrometers to measure the diameter and concentricity of all the journals and compare these to the factory specifications to determine what amount of wear had taken place over the life of that engine/crankshaft. Then you also carefully inspect all the surfaces of the old bearings and the crankshaft journals with a magnifying glass for any wear, grooves, scratches, etc. If the crankshaft is within specs, not worn and all the journal surfaces are still like new, then you can reuse that crankshaft. If not you most often send it out to have all the journals ground down smooth and use oversize bearings to make up for the material that has been ground off.
Factor #2, is that one of the two captains who had been hired to take Möbius out on sea trials prior to Christine and I accepting the boat from the builder and taking full possession and responsibility of the boat, did not have any experience or knowledge of CPP or Controllable Pitch Propellers. It did not seem like a major issue at the time as I explained how they worked and showed him how to slowly move the Pitch lever at the Helm forward to increase the Pitch angle and cause the CPP prop to “bite” or grab the water more and more to pick up boat speed through the water. I showed him the Pitch gauge and explained that he needed to increase the pitch very slowly and not to take it past half way during this first test while we were “breaking” everything in.
With the engine being brand new and coming up to temperature for the fist time, there was some smoke coming off the engine from all the new paint and left over bits of grease and oil from working on the engine so I had left the Helm and gone back to keep a close eye on Mr. Gee as he went through his paces. While I was there I tell from the sound that the engine was under a lot of load and I saw that the oil pressure gauge had dropped to just below 20 PSI and I immediately pulled Mr. Gee’s shutoff lever and shut him down. But it was too late, the damage as it turns out had already been done!
What had happened was that the Pitch lever had been pushed all the way forward which dialed in the maximum pitch angle on the four massive prop blades and with Mr. Gee running at lower RPM of about 1100 this massive sustained load had caused the brand new bearing surfaces to rapidly wear under the load as the original crankshaft journal surfaces labored over them. For those of you who have driven a standard shift car or truck, this would be like trying to climb a steep hill in high gear with the “pedal to the metal”. You get the idea!
Now the puzzle pieces all fell into place; the huge loads on the new bearing surfaces had worn rapidly which increased the microscopic space where the oil normally keeps the two surfaces from touching and so as this space increased with the ongoing wear, more and more oil was able to escape or “leak” out the sides and fall back into the oil sump. A vicious cycle then repeats itself with more wear leading to lower oil pressure which leads to more wear which leads to ………… where we are today!
While disappointing to say the least, at least I was now confident that we had found the true cause of the wear and the low oil pressure and Michael added that he had seen this exact same scenario play out on several Gardner powered boats over the past 20+ years so I can at least SWAN and get on with putting Mr. Gee back together again with his all new crankshaft, bearings and even more TLC than I already lavish upon him.
OK, back to our regular Show & Tell programming!
In Go the Pistons
When I left off last week, I had installed the new crankshaft and main bearings so now it was time to install the pistons and their con rod bearings which you see here as they come out of the Gardner factory box. Here are two of the six pistons as I prep them to be installed. Yes they are massive, each piston displaces a volume of 1750cc on each power stroke. NO! that is not a typo, that means that the volume of each one of these six cylinders is larger than most 4 cylinder engines in the cars you drive! Each cylinder has been freshly honed to create the Goldilocks surface finish for the new rings to all seat in just right. This original Gardner illustration out of one of the manuals I have will help show the relationship between the pistons, crankshaft, connecting rods, etc.. Each piston is liberally coated with clean engine oil and then very gently lowered into its cylinder.
Each of the three rings are then compressed so that they fit inside the cylinder and when the last ring is in the piston slides down the last bit to where the top con rod bearing rests on the awaiting con rod journal. Next I rotate the crankshaft 90 degrees to put the con rod at its lowest position so I can install the bearing caps. The coloured plastic tubes are there to make sure that the four con rod bolts can never Nick (remember him??) the journal surfaces as it is lowered in place. Now I can slide each con rod bearing cap in place over those four bolts and cinch down the nuts in stages to the Gardner specified torque. Here is the last Piston/Con Rod on Cylinder #6 with the protective cardboard wrapper still on the journal which I now remove, turn the crank 90 degrees to put the journal up at Top Dead Center or TDC and lower Piston #6 in place.
A classic example of just how and why Gardner engines are so robust and long lasting is this added feature that creates one of the most solid “bottom ends” of any engine I know. In addition to the massive aluminium caps that hold the main bearings in place, these two cross rods run through each of those caps and create a super solid main bearing system to keep that crankshaft rotating merrily for many many years. Once all 12 of those cross rods are torqued down and all the pistons have been installed and their caps fully torqued down the “Bottom End” as it is called is now all assembled and the last remaining item is to install the external pipework assembly that takes the pressurized oil to those holes you see in the flat oval bosses with 2 bolts in them here.
Main Bearing Lube Oil Pipework Assembly
Here is that lubricating oil pipework’s all disassembled ready for final cleaning and then installation of the sealing O rings that go inside each of the cast iron junctions that bolt to the main bearing caps you see in the photo above. Five of the seven main bearing fittings are assembled here and then ……. …… they slide into this T junction where the oil comes in from the oil pump and filter and get distributed fore and aft to all 7 of the main bearings.
BTW, for those wondering why the wear on the bearings #1 and 2 up at the front was the most and then became a bit less as you went aft, you can now see why as bearing on Cylinder #1 is at “the end of the line” or furthest away from the source of the oil pressure. So as the wear began and the oil leaked out, the pressure drop became progressively greater as it worked its way back from this T joint.
Piston Head Clearance
I won’t bore you with the full installation but there are lots of critical dimensions that need to be measured as you assemble a new engine and one of these you see here which is measuring the exact distance from the top of the piston to the top freshly ground surface of the surrounding cylinder block. I set up my dial indicator on top of the piston and move the piston to exactly Top Dead Center TDC and set the dial to Zero at this position. Then I rotate the dial indicator so that the pointer now rests on the cylinder block surface and check how much higher this is.
If you look at the photo above you can see that the difference is 0.015 or 15 thousandths of an inch and the factory specification is that it must be between 0.012 and 0.020 so this is Goldilocks “just right”.
Heads Go On
With the Bottom End all now fully assembled it is time to move up top and put the two heads back on. Freshly cleaned studs are all installed with Loctite to keep them properly torqued for the next 50 years.
Wondering what all the black “donut holes” surrounding each cylinder are?? These allow the coolant (water + antifreeze) to circulate between the lower cylinder block and the upper heads to keep everything at just the right operating temperature which in the case of a 6LXB is quite low at about 60C / 140F whereas modern engines run at about 80 – 95C. Obviously that coolant needs to say where it belongs and not lead out into the cylinders so this is the smart simple way Gardner seals each connection. The silver ferrules slide through the fat O-ring and them you press fit this assembly into each hole in the cylinder block. When the head is bolted down it squishes each rubber O-ring to form a permanent watertight seal. Thin steel head gaskets go on next to create the extremely critical seal that keeps all the huge pressures created when each cylinder fires to stay inside and provide the massive “push” of each piston as it travels downward creating all the HP and especially so the massive torque or “twisting power” that Gardner engines are so renowned for. Everything all done in the Engine Room and now time to prep the cylinder heads to be installed. I’d estimate that Mr. Gee had a total run time so far of less than 5 hours so it was pretty quick and easy to clean up each head and the valves of the carbon deposits from that run time. My best guesstimate is that each head weighs about 70kg/155lb so hoisting the off my workbench and up on top of all those studs and lining them all up so the head slides down onto the cylinder block is some eXtremely good eXercise! Front head goes on first as I have to slide in the ground shafts that each valve rocker arm rotates on so I install all the rocker arms, push rods and decompression levers first and then hoist the aft cylinder head into place and do the same valve assembly to it.
One of the last steps before I can lower Mr. Gee back in place and attach him to his buddy “Normy”, the Nogva CPP gear box, is to lift that humungous flywheel back up and slide it onto those 6 big studs you can see sticking out of the aft end of the crankshaft in the bottom Right.
I’m in fairly good shape and so is Christine but this flywheel is about 125mm/5” thick solid steel and weighs in at a svelte 120Kg / 265lbs so I used my brains instead of my “brawn” and rigged up some of our triple blocks that we will use to hoist our Tender Davit up and down and rigged them with some stronger than steel Dyneema line to make it eXtremely easy to lift the flywheel back up in place and line it up with all those bolts. Once I had torqued down the six bolts that hold the flywheel solidly onto the end of the crankshaft I could lift the other half of the flywheel housing in place and bolt those two halves together. This solid pair of housing create the big flat surface for the two rear engine mounting brackets to bolt to so they go on next. I custom designed these last year and we fabricated them out of 25mm / 1” thick AL plate that is TIG welded together and then each of these have the vibration dampening engine “feet” or mounts bolted to them and these feet are then bolted to the 25mm thick engine beds below. This is where I left Mr. Gee hanging a few hours ago and while it was Fathers Day today, it felt appropriate that as Mr. Gee’s “Dad” I should be giving him all this TLC and attention today.
I hope all you Dads out there had a fabulous Father’s Day that was just right, just for you!
So this is where I will also leave all of you “hanging” for this episode of As Mr. Gee Turns and I hope to have him fully mounted and possibly running again in time to bring you perhaps the final episode of the season!
Thanks for your time to join me here today for this latest Möbius Show & Tell, and please come join me again next week to find out how this season ends and I do hope you will add your comments and questions in the “Join the Discussion” box below.