Say it isn’t so?!! We’re heading into the last week of the year? How the heck did THAT happen so fast??
In my naïve youth I used to think that time would slow down as you got older and especially when you “retired” but I’ve never been busier in my life and time has never whizzed by faster. I think that the reality is that time is one of the few constants in life and doesn’t care how old we are, how busy we are, how much we need to get done, it just ticks away like some rock solid metronome one second at a time. Back in 2009 I recall a similar year end experience in what was then my second year of single handed sailing around the world in my former sailboat sv Learnativity, where I was recalling all the different experiences I had been through in the past two years and not being able to believe it was possible that ALL that could have happened in just two years. Drove me crazy for a week as I was sure that somehow my “math” was wrong because it MUST have been more like fife years. But nope, it was just two. Over time, hehehe, I came up with the notion of Learning/Living Density or simply Experiential Density and that is perhaps the variable; same amount of seconds in the year, just varying amount of experiences, learning and living for each of us. Whatever the case 2019 has been a year VERY densely packed full of awemazing experiences and learning for Christine and I and I would hope that is the case for all of you as well. But enough philosophising and let’s get busy reviewing the density of experiences building Möbius this past week of December 16-21, 2019
STEERING SYTEM:
As per part of the title there was some eXciting progress with on the Steering related equipment on XPM78-01 this week as well as many other systems and I’ll take you through all of those as well, however steering is perhaps THE most important system on any boat and especially on a power boat and eXceptionally so on an XPM given the eXtremely remote locations we and other eXtreme Passage Maker type boats tend to roam. On a sailboat if you were to lose all your steering such as having your rudder fall off then it is relatively easy to steer the boat using the sails. Ask me how I know! However with no sails if we were to ever somehow loose ALL steering capability on Möbius about the only option we would have would be to use one or our drogues or other warps you can fashion from long knotted or weighted lines and drag them off the Swim Platform and change the direction of the boat by moving the attachment point from side to side. All that being a VERY Waynewinded way of saying that we take the Steering System on the XPM’s VERY seriously. Uğur will help give you a better sense of size and scale of the rudder so you can see that it is both eXtremely strong and eXtremely big.
The other photos above show the rudder in various stages of construction and it is now all complete and ready to be installed so let’s go check out this week’s progress. These are the pair of self aligning PETP roller bearings which I worked closely with Thor Christen Hermann. the Systems Designer at Jefa Rudder Bearings in Greve Denmark to get them just right. Thor and everyone at Jefa was fabulous to work with and I can recommend them highly for any of your rudder related needs.
In the photo above the bearing on the left is the top bearing, lower on the right and the white ring in the middle is a thrust bearing to deal with any vertical forces and the black ring is anodized aluminium lock ring that is secured to the Rudder Post with locking setscrews. This section view from Jefa clearly shows how these bearings are mounted inside the yellow coloured rudder tube which is an integral component welded into the hull’s framing. A closer look at the lower bearing lets us see the black rollers for the 127mm/5’” aluminium Rudder post to smoothly glide on and down by my thumb you can see how the white inner race with these rollers inside, rotates inside the white spherical outer race which is fasted into the top and bottom of the Rudder Tube as seen above.
Next up, the 200mm/8” thick walled aluminium Rudder Tube is tacked in place after being precisely positioned with laser levels such that it is perfectly aligned in all directions and exactly on the centerline of the hull.
Let’s go see where those beautiful tendrils of smoke are coming from?
Aha! Now that Uğur and Nihat have tacked the Rudder Tube into position and also tacked on the additional 25mm/1” thick support braces, everything can be fully welded into the hull. This is one of the last major welding jobs to be completed and only leaves the installation of the Nogva CPP propeller and shaft to literally float our boat in the sense that she will be fully watertight.
Naval is using the latest Pulse MIG welders and in photos like this one you can actually see the pulses refracting the light which I thought was cool. Good comparative shot of the tack welds and the fully finished welds around the circumference of the Rudder Post where it exits out the top of the curved 15mm/ 5/8” plate of the Prop Tunnel. That same area now fully welded on the inside …. … bottom of the Rudder Tube fully welded on the outside….. … and top of the Rudder Tube fully welded to the Rudder Shelf inside the very aft end of the Workshop area. Door on the left puts you out on the Swim Platform.
Once everything cooled down the Jefa Rudder Bearings could be test fit into the Rudder Tube and we are looking up from under the boat to see the bottom Rudder Bearing here.
Next step will be to pump a special adhesive through a hole drilled through the side of the Rudder Tube and out a hole in the other side to fill up the special groves in the outer white bearing race and solidly affix the outer bearing to the Rudder Tube. OK, we’ve got a Rudder, we’ve got a Rudder Tube and Rudder Bearings, but how do we TURN the Rudder?
Oh right! The Tiller Arm I designed and has now been fully machined and fresh off the table of the CNC milling machine over at Tasot. If you’ve been following these weekly progress updates recently you’ll recall seeing this at huge block of aluminium being machined into the finished beauty you see here. I walked over to Tasot a few days ago with my rolling cart and brought this work of art and engineering over to Naval to test fit it to the Rudder Post.
Easy to see how these two halves will be clamped to the top of the Rudder Post with four long M16 bolts running through the four holes in the wings of the body of the Tiller Arm. These hardened and precision ground 25mm/1” OD pins are a close sliding fit into the Tiller Arm. Providing a super strong axis for the Heim joint ends of the two big Kobelt hydraulic steering cylinders we will see shortly below. Locking nuts threaded onto the ends of these pins will hold them in place. Back at Naval now for the first test fit. I have implicit trust in 3D models and the precision of CNC machining but we didn’t take the Rudder over to Tasot while the Tiller Arm was being machined so it was a great feeling to set this half onto the Rudder Post and have it fit perfectly! And of course the other half fit just right too.
Note the 18mm wide keyway cut into the top of the Rudder Post and in the photo above you can see the matching keyway cut into the Tiller Arm body.
The large through hole at the top of the Rudder Post is also part of the Steering System, the very end of the chain of redundancy and backups. There is a 70mm/2 3/4” OD thick walled aluminium pipe that is 2m/6.5′ long that can be inserted into this hole in the top of the Rudder Post and be used as an Emergency Steering Tiller. At the other end of this Emergency There are attachment points for block and tackle lines to run from the end of this Tiller to the hull frames on each side which would be used to lock the Tiller pipe in any location and move it as needed to steer. Obviously a bit of kit we hope to never use, though we will test on sea trials, but all part of the “belt and suspenders” approach we take for Steering and throughout the whole boat which enables us to be “Ready for the Unexpected”.
Continuing with this “knee bone connected to the thigh bone” and connecting the dots of the Steering System components, we now need to connect the Tiller Arm to the Kobelt hydraulic cylinders and that is what this next bit of Steering beauty is for. The bronze part in my hand is technically referred to as a Heim joint which is a spherical ball and socket type of joint which transfers the force from the Steering Cylinder to the Tiller Arm.
Kobelt equipment is eXtremely robust with their two favorite materials being bronze and stainless steel which you will be seeing a LOT of in the coming weeks as we get all the Kobelt equipment installed. With this Heim joint you can see how it is built to last for thousands of hours at sea with very little maintenance. A quick squirt of grease in that Zerk fitting to ensure these spherical SS ball and bronze socket are well lubricated and don’t wear is about all that should be needed throughout the long lifetime of these critical joints. OK, so now the Heim joint connects to ………???
This next example of the result when art meets engineering are these Kobelt 76mm/3” ID 7018 Hydraulic Steering Cylinders. The mounting base is where the cylinder is through bolted to thick pads on the Rudder Shelf you saw earlier. This is another SS/Bronze spherical joint the same as the Heim joint at the other end just encapsulated in this cast bronze base and again a simple Zerk fitting to keep this joint well lubricated, friction free and long lasting. And the Heim joint threads onto the other end of the SS shaft Steering Cylinder tom complete the Steering System’s connection to the Tiller Arm. But wait! What causes those big beefy hydraulic cylinders to move in and out you might ask, and I’m so glad you did.
Because I get to show you the final entry into this week’s Art & Engineering Beauty pageant, these Kobelt/Accu-Steer HPU400 Hydraulic Power Units. The anodized blue assembly on the right end is the very powerful hydraulic pump and the white cylinder under my hand is the 24V motor that drives the pump. There are two of these two speed pumps, one for each cylinder and we designed these with Kobelt engineers such that one pump and one cylinder exceed the steering requirements under the most severe conditions. Most of the time we will run them this way, one pump/one cylinder and alternate between the two every day or two when we are on multi week passages so we know they are both working and to keep them balanced for wear and use. If conditions were severe we can chose to run both pumps and both cylinders at the same time for even more power. In situations such as close quarter maneuvering such as docking in tight spaces, we can switch the pumps to their high speed and cut our 45 degree lock to lock time, 90 degrees total, in half.
Stay tuned for upcoming episodes where we are installing these pumps.
Some of which Cihan (right) and Okan already got started on this week as well. They are busy making the two AL shelves to mount the two Accu-Steer HPU400 suspended above the Tiller Arm in the aft end of the Workshop. The shelves have flat bar edges so that any spills of hydraulic oil over time are contained and easy to spot as well as easy to clean up. The three L-bar pieces tacked in place are for the six SS and rubber isolation mounts that secure the HPU pumps in place and keep them running silently. Next week you’ll see these shelves being mounted.
Whew! And that only gets us through this week’s work on just the Steering System so let’s move on to the next area of progress; plumbing!
PLUMBING:
We’ll stay with the multi-talented team of Cihan and Okan as they work on more of their plumbing jobs down in the Basement. While they were in the fabricating mood and tools they built this support rack for the Potable/Drinking Water tank. This poly tank is another example of the “Readiness for the Unexpected” approach in that it will hold 210L / 55 USG of fresh water that will be kept independent of the rest of the boat’s water tanks and domestic water systems. It will be plumbed to an independent water pump and connected to a second faucet at the Galley sink.
The only potable water we allow onboard is what comes out of our 200L/52USG per hour watermaker, never any shore side water so we know the quality of the water is the highest, being essentially pure H2O. However, there is always the chance, however remote, that the water in the six integral aluminium hull tanks could get contaminated or even more unlikely could escape. So this tank with its own pump and filtration system will always be at the ready just in case the unexpected should happen.
The white unit on the right is the Vacuum Generator for the Guest Cabin VacuFlush toilet.
Above the VacuFlush Vacuum Generator is this manifold which controls the hot water flowing to the three zones of the in-floor heating in each Cabin. Cihan has done his usual masterful job of installing these manifolds and picking up where we left off last week. Domestic Hot Water DHW from the IsoTherm Calorifier flows into the red handled shiny SS upper Supply manifold and then out the three fittings with the red flow meters on top.
Zone 1’s gray PVC/Red handle ball valve is dry fitted in the center to help determine the location of the circulation pump mounts which are the two aluminium L-bar pads on the right. Zone 2’s pump will mount on the pads you can just see at the bottom right and more fully in the photo below.
After circulating through the 15mm PEX tubing embedded in the floors in each zone, the slightly cooler water flows into the bottom of the polished SS Return manifold through the 3 SS threaded fittings below the 3 white flow control valves and returns the water back to the Calorifier via the black insulated PPR pipe with the blue handled SS ball valve.
There is a temperature gauge on both the Supply and Return lines to make it easy to see the temperature differential and performance of the system. The vertical SS units on the left ends of each manifold are for draining/filling the system and for bleeding off any entrapped air.
These are the AL brackets which Cihan has come up with for mounting each of the three speed Zone Circulation Pumps to the bulkhead. Here is the completed bracket test fitted to one of these pumps. Longer bolts will be used with an additional nut on each end to keep the clamping of the pump’s sealing flange independent of the mounting nut. Each one of these pump mounts will be bolted to those pads you saw in the photos above with rubber noise isolation separating the mounting bracket from the pads and keeping noise and vibration locked up in the Basement.
NOGVA CPP PROP & SHAFT
Well, let’s give Cihan and Okan a bit of a rest and move on to the ever busy Aluminium team of Nihat and Uğur.
After spending the weekend in the freezer to shrink, the orange coloured Cutlass bearing was pressed into the outboard end of the Nogva Prop Log Tube you saw being installed last week. The groves in the upper half ensure that water flows freely out of the tube and provides a steady supply of clean water to lubricate the prop shaft. When rotating the prop shaft “floats” on a thin film of water so that the Cutlass Bearing material and the prop shaft only touch when the prop is not moving.
That all set the stage for the Nogva CPP Controllable Pitch Propeller to be test fit. The smaller diameter end of the CPP prop hub at the bottom here is what fits inside the machined AL housing you see in the photo above. The stepped flange slides in about half way 20mm/3/4” into the AL housing and acts as a rope guard when, never if, you happen to snag a lobster pot, fish net or other underwater debris. At the opposite inboard end of the CPP Prop Shaft is the push/pull rod that runs inside the hollow prop shaft all the way from this threaded end to inside the bronze CPP prop hub. As this rod is moved fore/aft by hydraulic pressure inside the Nogva CPP servo gearbox the bottom end of each of the four prop blades is rotated in synch to change the pitch from zero to full forward or full reverse. Okan then gave the whole prop and shaft a thorough cleaning and a small army of men picked up the eXtremely heavy prop/shaft assembly and carefully slid it through the Cutlass Bearing until that stepped bronze end of the prop hub was the correct 20mm inside and attention can now turn to positioning the mounting brackets for the Nogva CPP Servo Gearbox inside the Engine Room and which we will pick up on in next week’s installment.
ALUMINIUM WORK:
Speaking of the Engine Room, Nihat and Uğur were busy in there as well this week. With that clue can you guess what they were working on based on this photo? Full marks to those of you who guessed Sea Chests! These are located at the very front end of the Engine Room with the larger Supply Sea Chest on the right and Exit on the left. There will soon be two Vetus strainers flange mounted to the two pipes coming out of the Supply Sea Chest which will then both feed a sea water supply manifold for consumers such as the Water Maker, Gardner heat exchangers for cooling engine oil and coolant as well as the Nogva heat exchanger and then exiting into the wet exhaust system.
The 25mm/1” thick Engine/CPP beds are the flat sloped surfaces running top to bottom in this photo, water tanks on either side of them with their respective access ports bolted in place and SAE flanges around them for tank gauge senders and fill/supply lines. Engine Room diaphragm Bilge Pumps can be seen on either side of the WT Bulkhead with the Guest Cabin/Office on the other side.
Not easy to get the MIG gun all the way down here but the welder did a great job of getting a full set of deeply penetrating welds around the circumference of this Supply Sea Chest.
WATERTIGHT DOORS:
Yet another exciting bit of progress was Nihat (left) and Uğur getting started on the frames for all the WT Doors! They started with this door on the Port/Left side of the Swim Platform that provides access to the HazMat where we can safely store any Hazardous Materials such as diesel, paints, thinners, etc.. This one door they will build entirely in house here at Naval and the others will be high end WT fully certified WT doors from Bofor.
Here they are fabricating and tacking in place the inner flanges for the HazMat door frame. Which they complete very quickly, With the exact sizes of the frame now set, they moved on to fabricating the HazMat door. And had that knocked out just as quickly. Next week they will fabricate and mount the hinges and seals. Sliding over to the opposite Stbd/Right side of the Swim Platform they tacked the inner frame flange for the Bofor WT door. These doors will be bolted in place with industrial adhesive in between to seal completely.
Bofor is custom building all the WT doors for Möbius to our specifications but will look similar to this one. To be fully WT certified there will be two dogs/locks at the top/bottom rather than one as you see here and our doors will be left unpainted AL to match the rest of the boat.
The WT off the Aft Deck into the SuperSalon will have a full length window whereas the one on into the Workshop and the one between the Guest Cabin/Workshop will have a single window like the example here. With the mounting flange tacked in place, Nihat trims it to final opening size for the Bofor door frame to set into. Cihan clowning it up to show how the door frame and flange look from inside the Workshop. The Accu-Steer pumps and Tiller Arm you saw earlier in this post are sitting off to the right of this photo. And before you know it the frame flange is fully welded in place and ready to have these corner welds cleaned up and radiused.
CABINETRY WORK:
More beauty to be found inside of Möbius this week as always. Omur, Selim and Omer often get to steal the show as their expertise and craftsmanship really shines as they work with the rich grain patterns of the Rosewood. This corner where the lower Freezer cabinet meets the taller Fridge cabinet is but the latest of many examples of their attention to detail with things such as matching the grain patterns to perfection. Stepping back a bit from that same intersection to show how the grain swirls forward onto the wall cabinet for the 50” monitor on the Port side of the SuperSalon and Main Helm. A few more steps back to show how the wall has been recessed for that large monitor. It will be on a HD swiveling mount which allows us to pull it all the way out of the cabinet, swivel it forward and aft and tilt it up down. This enables us to use this screen for both entertainment viewing of movies and photos from either the Lounge chairs or the Settee for our “dinner and a movie” nights and then quickly reposition it for ideal viewing from the Helm Chair when underway. Yet another example of Ömür’s creativity and craftsmanship are these little cut outs so you can easily slide your fingers round the back of the monitor to pull it out.
Over in the Cabinetry Workshop with his compact sold edge router in hand, Omer shows one of his latest examples of grain matching mastery on this panel that will soon go into the Guest Cabin. Back aboard Möbius and down in the Master Cabin, Omur and Selim start a new job of fabricating the laminated Rosewood liners for the insides of each of the ten hatches we designed and built in house. They use this special laminating material which as you can see is extremely flexible and can be easily shaped and formed however you wish. Solid wood corner blocks are glued in place to provide the backing for the large radius corners of each hatch. Then successive thin layers are glued up, let dry and the next layer applied.
We will pick up on this process next week as the laminations continue and then the solid Rosewood edges and veneer goes on to finish these beauties off.
NEW ARRIVALS THIS WEEK:
The pace of ordering picks up as we get nearer the end of the build so there are more and more new arrivals showing up each week now and here are a few quick examples to leave you with.
Like these four bolts of leather for our interior walls and ceilings!
One bolt of black leather for the Helm Station surfaces and ceiling above to minimize reflections, one bolt of white leather for the removable ceiling panels and two bolts of this gray/green leather for the upper wall panels. Can’t wait to see and be able to show you these as they get installed! And then five cartons like this one from LiteMax in Taiwan.
Can you guess what’s inside?
Yup, our five sunlight readable monitors!
Two 19” ones side by side at the Main Helm station, two 24” side by side up in the SkyBridge Helm and one 43” on the Starboard/Right side of the Main Helm Chair.
I think Captain Christine likes them. As well she should as she spent months researching and tracking these down. Our requirements are eXtreme as usual as we need monitors which are:
Full Sunlight readability (1000 nits+) most new smartphones are about 200-280 nits
Dimmable all the way to black for night watches using real front mounted buttons and knobs
Multi-Touch enabled (PCAP) same as your phone
SXGA resolution 3840 x 2160 or better
Waterproof & Ruggedized
Oh, and affordable too please!
A tall order to say the least and Christine and I would like to give an eXtremely BIG shout out and thanks to Peter Hayden of mvTanglewood fame for all his help in the early stages of this search as a result of all his efforts in searching for monitors for his previous Nordhaven 62 and now the new N68 he is having built. Peter had tracked down several of the companies who are the OEM Original Equipment Manufacturers for these kind of high end monitors for the marine industry. If you are not familiar with Peter’s work on mvTanglewood and his constant flow of expertise on the Trawler Forum, do yourself a favor and go check this out ASAP. Peter is an endless source of great ideas and expertise and writes outstanding explanations of his work and experiences. A MUST read for Christine and I and we hope to share an anchorage with our two boats in the not too distant future.
This led us eventually to LiteMax in New Taipei City in Taiwan who make the monitors for airports, railways, stadiums, ATMs and the like and who were willing to make us the Goldilocks just right monitors for us. It took several months of working with them to get these speced and built and then air freighted to us here in Antalya but they arrived his week and we could not be happier as you can see from my Captain’s face!
They only arrived on Friday and we had a busy Saturday with no time to do anything more than unbox one but we hope to get them setup and tested next week and will bring you more details then. Just one of the literally thousands of decisions we make and problems we solve every week on this grand adventure of designing and building our just right new boat and home.
Thanks for joining us, please put your comments and questions in the “Join the Discussion” box below and we’ll see you here again next week.
– Wayne & Christine
8 Comments
Andy on December 23, 2019 at 2:44 pm
The steering system looks very well thought out and components very robust.
However, a couple of suggestions:
1) Maybe consider adding plumbing/valves to enable optionally parallel connecting the cylinders and thus double the effective displacement. This makes steering slower for passages and thus steering more smooth, and makes sure all the fluid is circulated/filtered constantly when only using one pump. You should have most of this in place already, if you have an option to parallerise the pumps already. As a bonus this doubles the max torque generated by the steeting system, but I guess this you do not need 🙂
2) Definitely consider adding a small, reversible non-constant running passege pump. I bet the boat steers and tracks really well and it is just a waste to run a big constant running pump circulating and heating up that hydraulic oil 24/7 on a passage when weather is good. One from hy-pro for example has internal pilot operated check valves so it can be hooked in parallel to hand steering pump with absolutely no other changes to the system. Even a couple of hundred watts of constant 24/7 load saved here is liters of diesel per day, small efficiencies do add up. Such a pump only costs a couple of hundred USD.
And some extra suggestions flagged “next/bigger/sister boat”, no need to consider these yet 🙂
3) If there is ever a time to upgrade/replace these cylinders or a next/bigger/sister boat being built, do choose the unbalanced ones. There is one less rod and one less set of seals exposed, I know Kobelt has those too in their selection – or go with an industrial much beefier (300+ bar) cylinder which costs quite a bit less and can be sourced anywhere as a spare part. With modern pumps and control systems the unbalanced cylinder is a non-issue and provides a bit more torque to extending direction as a bonus due to a little bigger cylinder effective area.
3B) Same goes to the steering pump. A piston based hydraulic pump is much much much superior to a gear pump in almost every way except it costs a little more, but not that much all considered. Main benefit is much much higher efficiency. I have had really encouraging results with energy savings (tens of percents) at my day job/work replacing old gear pump based hydraulic power packs with modern permanent magnet motor servodrive driven piston pumps with all electronic control, no lossy valves involved. Greater precision, no idle consumption, less moving parts, way simpler system – diagram is 10x less lines, higher efficiency.
*) I estimate HPU400 takes 10-15A idling current at 24VDC when not steering, only circulating oil. This translates to around 6-8 kWh per day, or roughly 3+ liters of diesel “wasted”. I might be not 100% accurate here, but magnitude is right.
I’m expecting better performance and efficiency than that but we’ll see once I get some good sea miles under our hull and will be reporting on all that once we set off.
3C) Almost forgot the most important bit. Always have your hydraulic reservoir a) pressurized – low pressure like 2 bar will do just fine – and b) sealed from outside air and moisture and dirt and whatnot and c) large enough (3 x working volume) for oil to “rest” and cool between cycles. This way your hydraulic system will last forever, 10000h+ of operation between maintenance breaks is easily achievable.
With our Kobelt setup the hydraulic steering reservoirs are simply that; reservoirs and they only serve to allow for expansion/contraction of the oil and ensure that there is always a “head” of supply oil for the system. There is no flow or circulation through these reservoirs so not pressurized or needing much volume. I had Kobelt steering, albeit smaller sizes on our previous steel sailboat so know them quite well and the reservoirs worked the same way and were the ultimate in KISS, just check them once in awhile to be sure the oil level was within range.
Good points as always Andy. Quick responses: 1. Already part of the original design so we are in agreement on the multiple ways we can configure the steering. 2. Might be something to look at in the future after I have some real world data on how the current design works out. I’m reluctant to add yet another system so the benefit would have to be significant. 3. Not a fan of unbalanced cylinders but will leave this decision to Naval and new owners. 3B. Thanks I’ll consider this for future pump setups.
Hey Mary & Mike! Great to have you join us for this adventure and can’t wait to have you aboard to try her out for yourself. Depending on how soon we get Möbius underway and fully sea trialed we may be able to make our Atlantic crossing in time to see you before the end of this year. Stay tuned here and you’ll know just where we are in close to real time.
The steering system looks very well thought out and components very robust.
However, a couple of suggestions:
1) Maybe consider adding plumbing/valves to enable optionally parallel connecting the cylinders and thus double the effective displacement. This makes steering slower for passages and thus steering more smooth, and makes sure all the fluid is circulated/filtered constantly when only using one pump. You should have most of this in place already, if you have an option to parallerise the pumps already. As a bonus this doubles the max torque generated by the steeting system, but I guess this you do not need 🙂
2) Definitely consider adding a small, reversible non-constant running passege pump. I bet the boat steers and tracks really well and it is just a waste to run a big constant running pump circulating and heating up that hydraulic oil 24/7 on a passage when weather is good. One from hy-pro for example has internal pilot operated check valves so it can be hooked in parallel to hand steering pump with absolutely no other changes to the system. Even a couple of hundred watts of constant 24/7 load saved here is liters of diesel per day, small efficiencies do add up. Such a pump only costs a couple of hundred USD.
And some extra suggestions flagged “next/bigger/sister boat”, no need to consider these yet 🙂
3) If there is ever a time to upgrade/replace these cylinders or a next/bigger/sister boat being built, do choose the unbalanced ones. There is one less rod and one less set of seals exposed, I know Kobelt has those too in their selection – or go with an industrial much beefier (300+ bar) cylinder which costs quite a bit less and can be sourced anywhere as a spare part. With modern pumps and control systems the unbalanced cylinder is a non-issue and provides a bit more torque to extending direction as a bonus due to a little bigger cylinder effective area.
3B) Same goes to the steering pump. A piston based hydraulic pump is much much much superior to a gear pump in almost every way except it costs a little more, but not that much all considered. Main benefit is much much higher efficiency. I have had really encouraging results with energy savings (tens of percents) at my day job/work replacing old gear pump based hydraulic power packs with modern permanent magnet motor servodrive driven piston pumps with all electronic control, no lossy valves involved. Greater precision, no idle consumption, less moving parts, way simpler system – diagram is 10x less lines, higher efficiency.
*) I estimate HPU400 takes 10-15A idling current at 24VDC when not steering, only circulating oil. This translates to around 6-8 kWh per day, or roughly 3+ liters of diesel “wasted”. I might be not 100% accurate here, but magnitude is right.
I’m expecting better performance and efficiency than that but we’ll see once I get some good sea miles under our hull and will be reporting on all that once we set off.
3C) Almost forgot the most important bit. Always have your hydraulic reservoir a) pressurized – low pressure like 2 bar will do just fine – and b) sealed from outside air and moisture and dirt and whatnot and c) large enough (3 x working volume) for oil to “rest” and cool between cycles. This way your hydraulic system will last forever, 10000h+ of operation between maintenance breaks is easily achievable.
With our Kobelt setup the hydraulic steering reservoirs are simply that; reservoirs and they only serve to allow for expansion/contraction of the oil and ensure that there is always a “head” of supply oil for the system. There is no flow or circulation through these reservoirs so not pressurized or needing much volume. I had Kobelt steering, albeit smaller sizes on our previous steel sailboat so know them quite well and the reservoirs worked the same way and were the ultimate in KISS, just check them once in awhile to be sure the oil level was within range.
Good points as always Andy. Quick responses:
1. Already part of the original design so we are in agreement on the multiple ways we can configure the steering.
2. Might be something to look at in the future after I have some real world data on how the current design works out. I’m reluctant to add yet another system so the benefit would have to be significant.
3. Not a fan of unbalanced cylinders but will leave this decision to Naval and new owners.
3B. Thanks I’ll consider this for future pump setups.
Truly amazing!
Hey Mary & Mike! Great to have you join us for this adventure and can’t wait to have you aboard to try her out for yourself. Depending on how soon we get Möbius underway and fully sea trialed we may be able to make our Atlantic crossing in time to see you before the end of this year. Stay tuned here and you’ll know just where we are in close to real time.