Electric propulsion Repower Lagoon 560 Yanmar 110 4JH110

[Ifitsworthdoing]

Hi ArranP - applaud your intentions in principle as I will be doing something very similar if for a considerably smaller boat (Broadblue 346 normally powered by twin 16HP Betamarines/Kubotas) next year.

However I agree with several of the commenters that some of your assumptions are overoptimistic: You will not need as much power (kW) for either engines or genes and would struggle to afford/spacially accommodate the battery banks and motor set-ups (also remember that the genset will need a significant fuel tank). The Silent-Yacht data you provide for comparison is company-generated, i.e. a best-case scenario rather than based on independent testing, and applies to non sailing yachts custom-designed for maximum solar estate size (I know they also build sailing yachts but their data does not reflect this).

I recognise your determination to do something exciting that creates a proper cutting edge eco technology boat - but working with existing off-the-shelf technology this will prove both technically challenging as well as very expensive and highly stressful. Hence my advice would be to temper your enthusiasm and accept that you will need to make compromises if you want to hold on to your sanity and life partner ...

IMHO your boat as a sailing yacht with supplemental motor propulsion would do perfectly well with 50kW motors and a 25kW genset (I am looking at using mine without a mast and rig as a power trawler with twin 18kW engines and 2 x 3.5kW gensets). Your battery bank would accordingly only need to be about 75kW (my trawler's one will probably be about 40kW) and the smaller it is the easier it will be to keep the operating voltage to below 50V (which has considerable insurance and regulatory advantages). Also keep in mind that with the accelerating pace of battery technology development your first battery bank is likely to be obsolete within its typical operating life of 8 years and will then be replaced by a much more capacious but smaller and lighter new set ...

[Scout 30]

I'd also love to convert to electric. Unfortunately, based on the current battery & solar panel technology & prices it just doesn't make sense for any cruising boat. More than double the initial cost for a very limited range & a significantly reduced return when you sell.

[aerocanard]

I have worked on 2 electric catamarans. Privilege 395 and a Tag 60. The Privilege was sold way less because it was electric instead of Diesel. It had a single genset 144 volt 17.5 kw. He could only cruise on battery for about a hour without using his genset. The genset would not charge the bank to full while using the motors cruising. The charger was too small for the bank? When the genset stopped because of over heating he was dead in the water. Any other genset issues that would make it not start or not run would not let the boat motor. So much for twin engine.

The Tag 60 was totally electric using twin diesel gensets at 144 volt. Battery management was a real problem keeping the LI batteries balanced. Again, about 1 hour run time with the batteries until the gensets had to turn on. Over heating motors under the beds were also an issue because they were not water cooled. The cost of the gensets, batteries, controllers, motors and the complexity of the install was overwhelming. There was a full time engineer on the boat trying to keep it all working. Boat speed under power sucked, the weight of the systems sucked. Every time he would leave for a week or so the systems would have to be reset and the batteries balanced again. 5 banks of LI took quite a lot of time to reset. It was double the cost of a normal diesel setup to move that boat at better speeds for longer cruising times.

If you plan to just day sail and not cruise, this option might be a little better. The amps you will draw with those electric motors will not allow you to have solar keep up with the power draw. This is not a KISS program. Keep is simple stupid. Last but not least is the weight of all of this systems. Cat's suck when they are overloaded. They also need to be balanced. Too much weight in the front or back make them pitch buck. The Tag 60 was the worse cat I have been on for pitching. The boat was overweight and not balanced.

Looking at all of the solar panels you want to put on and the single engine genset that is huge, big battery banks and so forth. Do your math on the weight.

The last thing I did not like was the high torque power on the props with trying to maneuver at a dock. It is like giving half of full power when putting the props in gear. Too much makes the boat react too quick.

Just because you purchase a salvage boat should not be a good reason to make it worse putting in systems that make no sense.

I repowered the privilage and the Tag 60 is also going thru a repower to standard diesels.

Hope that helps

Jeff Russell / Mack Sails
SV Vitesse
Jeanneau / Lagoon 55s

[GrowleyMonster]

I am a big fan of PMAC (also called BLDC, Brushless DC) motors in smaller boats. They are readily available and very cheap up to about 12kw. Controllers for same are fairly cheap up to about 300a and 144VDC into the controller. However at the power levels you are looking for, the cheap way to go is a repurposed automotive electric drive motor, typically this being an inductance AC motor. Also, while there are a lot of very good reasons to stay below 48v at lower power requirements, for anything over the 12kw level or so, you want much higher voltage and in the 300's is not unreasonable. I would say at least go 144v nominal. Higher voltage equals lower current for the same amount of work done.

It sounds like you want to match your old engine's performance. To do that, if you include range/duration, you will most certainly need a genset for extended operation. Ideally you would have a big one that can maintain or even increase your bank's charge while running the motor at full power, and also a smaller one for when you do not need the big one on line. Solar at best will keep you going indefinitely at very low speed, and only if you remember that it is a boat and not a floating mansion with central AC, dishwasher, electric oven, etc running all the time.

Big electric motors have relatively low overhead. Running a 12kw motor at a 2kw output, and running a 5kw motor at 2kw output, consume virtually the same energy. I can tell you this from actual experience. Running a big diesel and a small diesel at the same speed and load will have the big diesel consuming a lot more fuel than the small one, generally speaking. So unlike diesel, with electric, there is no good reason to go with small motors. It costs little or no extra energy to run the bigger motor, plus you have the higher power capability.

You will need a large solar array for topping up your batteries and float charging. This is the part that a diesel generator is not very efficient for. Ideally the diesel is used in the bulk charging phase only. But for a really big bank, the demands on a battery in Acceptance or Float charge mode are significant. Your solar array will NOT keep up with your energy consumption when your motor is running at full or even cruise power setting. Take my word for that, or find out for yourself. No skin off my nose.

The supposed inefficiency of using a diesel to charge batteries to drive an electric motor are actually fairly small, in a WELL DESIGNED and WELL OPERATED system. But there is no free lunch. You will have SOME conversion losses that are only partially offset by the operational flexibility including the ability to motor at extremely low speeds when desired.

The biggest advantage of electric? No bumping in and out of gear when docking or otherwise proceeding at very low speeds. No minimum idle speed, for all practical purpose. If you want to approach a dock at 30RPM, you can. If you want practically instant torque, you got it at your fingertips. No warmup. No start sequence. Flip a switch and turn a knob or move a throttle lever and away you go. Great for tacking single handed on hardnosed boats.

Just like you can't rely on solar for the bulk of your energy requirements, neither will you get a free ride from the regen. Sure, it helps, just like solar helps, but it takes a LOT of sailing to charge the size bank you will need. Been there, done that.

The best use case for electric is a boat that is pretty much only sailed, that requires mechanical propulsion only for ins and outs, clearing bridges, etc. and in that use pattern, it is absolutely marvelous. For extended or extensive motoring at typical diesel speeds, it is almost certain that your system will fail to achieve your expectations. One way around that is to lower your expectations. A lot. The other way is to increase your ICE electrical power generation capability and figure on burning significant amounts of diesel, though not as much as a straight diesel propulsion system, assuming your EP system is well designed. Simply put, an electric boat with the same range and power as a diesel boat will get the majority of its power needs from diesel, supplemented with solar and regen. Most prospective electric boaters believe it will be just the opposite, with the renewables providing the bulk of power needs and the generator there just to supplement regen and solar. It doesn't work that way unless you are okay with motoring at 2kts or so. Another issue is shading. Sails, mast, even rigging will shade the solar panels enough to seriously impact your energy harvest. Cloudy weather, and low sun elevation in morning,evening, and winter outside the triopics, will impact your solar energy yield. Regen can be significant if you are sailing at 13kts but pretty meh at 3kts.

A 10kwh bank is insignificant for the system you envision. My Cal 2-27 had 10.5kwh and I considered adding a second bank just like the first.

If you SAIL and only motor when absolutely necessary, you will probably love electric propulsion. If you want to motor day and night at 6kts, you will be running a fairly large diesel genset the whole time.

If it were my boat, with my preferences and usage pattern in mind, I would opt for either one or two 12kw Motenergy PMAC motors in each hull, belt driving the prop shaft, and a separate bank for each hull consisting of 16 GC-2 size 6v golf cart batteries in series. Certain performance tradeoffs would be dealt with or just accepted, remembering that at one time NOBODY had an engine AT ALL. I would not mess with water cooling. There would be places I would not be able to go. There would be other places I would only be able to go in favorable conditions. The world's oceans would mostly be open to me. I would know to stay well clear of lee shores and be very aware of the weather and how a change can endanger my boat. If those limitations were unacceptable, I would install diesels, maybe smaller ones since IMHO nearly all boats with diesel auxillaries are greatly overpowered.

I highly recommend you spend a couple of years research before you start spending money on this project. Even better, buy an old Catalina 30 or 27 or similar that has a non running Atomic 4 in her, and repower it with electric. You can do it for under $3k if you are careful how you spend your money, and maybe another $3k for the boat. It is a lot easier to make EP work well, with a smaller boat. You will learn a lot and probably have a lot of fun tinkering and operating. A good system using a pure sine wave controller can be very quiet. Very responsive, too. Low maintenance, no pumping or spilling or purchasing of fuel. For day sailing, shore power charging will be all you need. For coastal cruising, you will quickly familiarize yourself with EP's pros and cons, in general. Put up a solar array. Record your data. Figure stuff out and make it real to you.

[Hyprdrv]

Watching this thread with...interest...

Steve in solomons MD
2004 Lagoon 410 S2E

[ArranP]

Knots / Rpm - Real Case :-

https://www.sailmagazine.com/boats/l...2C700%20miles.
Excerpt "Capt. Herve, who had just sailed the boat across from France, said he was able to get 6.5 to 7 knots out of the boat at 2,000 rpm on one engine" ( highlighted in YELLOW on the table )

Formulas :-

WEN Technology - Calculators
kW = ( Speed Rpm x Torque Nm ) / 9550

https://www.rapidtables.com/convert/power/hp-to-kw.html
HP = kW / 74.57%

https://www.go-fast.com/Knowledge-ba...eed-calculator
Boat Speed knots = ( The Square Root of ( HP / Laden Weight lbs ) x Constant ) x Sea Margin

Figures :-

86,840 : Laden Weight ( 130 % Dry Weight 66,800 )
275 : Constant for catamaran https://www.go-fast.com/Knowledge-ba...eed-calculator
85% : Sea Margin

Table :-

Without consideration for generator and its fuel tank.

Battery Bank - 300kWh

Using the two 688 litre diesel tank ( 672 kg ) spaces to accommodate each a battery bank upto a maximum of 150kW ( 1350 kg ).

PV Panel Array - 33kWh per day

7 rows of 4 columns x 500W per panel a total of 14kW, apply a performance reduction of 60% of maximum due to shading and multiply by 4 sun hours per day.

Total energy available for motorsail - 330kWh ( 300 + 33 )

Duration / Range ( Electric Propulsion ONLY ) : 12 hours / 60 miles

I calculate it is possible to motorsail 12-13 hours at 4-5 knots and cover a range of 60 miles, then a peirod of 4-6 days is required to recharge the batteries. ( highlighted in GREEN )

ReCharge Time - 5 to 6 days

300 kW battery bank / 33kW collection via PV Array per day circa 5 to 6 days until fully recharged, depending ability to minimise shading whilst stationary

[Yihang]

some inspiration.

https://www.yachtingworld.com/featur...ainable-126310

[Tupaia]

Originally Posted by ArranP

https://www.go-fast.com/Knowledge-ba...eed-calculator
Boat Speed knots = ( The Square Root of ( HP / Laden Weight lbs ) x Constant ) x Sea Margin

This is for a Pleasure Type Catamaran and has no inclusion of LWL that would suggest a planning or semi displacement power cat. A sailing cat is likely to have considerable windage and be constrained by LWL


Using all the 220hp available I would suggest a boat speed of about 9.5-9.6 knots less than 70% of your estimated 14 knots @ 225hp

[ArranP]

Originally Posted by GrowleyMonster

If it were my boat, with my preferences and usage pattern in mind, I would opt for either one or two 12kw Motenergy PMAC motors in each hull, belt driving the prop shaft, and a separate bank for each hull consisting of 16 GC-2 size 6v golf cart batteries in series. Certain performance tradeoffs would be dealt with or just accepted, remembering that at one time NOBODY had an engine AT ALL. I would not mess with water cooling. There would be places I would not be able to go. There would be other places I would only be able to go in favorable conditions. The world's oceans would mostly be open to me. I would know to stay well clear of lee shores and be very aware of the weather and how a change can endanger my boat. If those limitations were unacceptable, I would install diesels, maybe smaller ones since IMHO nearly all boats with diesel auxillaries are greatly overpowered.

I like this idea, to have both an electric motor and the existing diesel engine as options to drive the prop shaft.

The diesel engine could double up as a genset by driving the electric motor to recharge the battery, thus making the original genset redundant.

This would require a interchangable tri-shaft configuration, that would allow

1. electric motor to drive the prop shaft
2. diesel engine to drive the prop shaft
3. diesel engine to drive the electric motor ( recharge battery )

Any idea where one can go to get a custom tri-shaft/transmission made ?

[atoll]

Originally Posted by ArranP

I like this idea, to have both an electric motor and the existing diesel engine as options to drive the prop shaft.

The diesel engine could double up as a genset by driving the electric motor to recharge the battery, thus making the original genset redundant.

This would require a interchangable tri-shaft configuration, that would allow

1. electric motor to drive the prop shaft
2. diesel engine to drive the prop shaft
3. diesel engine to drive the electric motor ( recharge battery )

Any idea where one can go to get a custom tri-shaft/transmission made ?

cummins build marine engines where you have power take off at both ends of the engine,on the back you mount your gearbox,on the front you mount the generator,above the prop shaft you mount your belt driven electric drive motor

[Munoz]

Originally Posted by ArranP

I like this idea, to have both an electric motor and the existing diesel engine as options to drive the prop shaft.

The diesel engine could double up as a genset by driving the electric motor to recharge the battery, thus making the original genset redundant.

This would require a interchangable tri-shaft configuration, that would allow

1. electric motor to drive the prop shaft
2. diesel engine to drive the prop shaft
3. diesel engine to drive the electric motor ( recharge battery )

Any idea where one can go to get a custom tri-shaft/transmission made ?

No need to go custom, not cheap, but they are already available more or less off-the-shelf: https://www.hybrid-marine.co.uk/inde...agoing-hybrids

[JustMurph]

Munoz is on the money.

IMO, the only electric setup that really makes sense on a cruising cat is a parallel diesel electric hybrid in one hull and an electric in the other. The diesel will have a pancake motor/generator on the back of it with a clutch between it at the motor. You over size the diesel so that it will have enough power on its own to push the boat continiously in storm conditions. The electric in the other hull and the motor/generator unit only need to be large enough for manoeuvring and say a 6 knots cruise.

In nice conditions, you leave anchor/marina on electric only, then sail. If you need to motor you have the power to do it and with direct drive it will be efficient. You can regen from both electrics when sailing. You can run the motor just as a generator with the prop decoupled. You can have a smaller battery bank.

This will be considerably lighter and simpler system.

[GrowleyMonster]

Originally Posted by ArranP

I like this idea, to have both an electric motor and the existing diesel engine as options to drive the prop shaft.

The diesel engine could double up as a genset by driving the electric motor to recharge the battery, thus making the original genset redundant.

This would require a interchangable tri-shaft configuration, that would allow

1. electric motor to drive the prop shaft
2. diesel engine to drive the prop shaft
3. diesel engine to drive the electric motor ( recharge battery )

Any idea where one can go to get a custom tri-shaft/transmission made ?

That's not the way. Use your normal transmission but only if it is safe to have the output shaft turning while in neutral.

Doesn't hurt anything for the electric motor to turn with no load. the motor is coupled to the shaft with a belt. You CAN use a belt drive clutch to remove the electric motor from the shaft but there is no need.

You can use a simple splined sleeve coupling to disengage the diesel's transmission completely from the shaft, if you add a thrust bearing to the shaft.

[ArranP]

Its been sometime since my last post, I thought I would share my latest findings... it appears I have found a suitable and economical motor & controller :-

HPEVS Curtis AC51 motor & Controller 1239E-8521 (144V 500A)

It's peak power is 65kw 144VDC nominal upto 500A, there is the option of an oil cooling system to both the motor and the motor controller for marine applications.

It appears to be suitable for regen braking for the purposes of marine this means it maybe possible to be used as a hydro generator or deisel generator to recharge the batteries.

The cost for 1 motor and 1 controller is circa 5000USD, additional items need to be purchased marine display, marine throttle, contactor, cables.

https://www.hpevs.com/index.htm

Peak Power Graph
https://www.hpevs.com/Site/images/to...peak_graph.pdf

Oil Cooling Continuous Power Graph
https://www.hpevs.com/Site/images/to...%204-15-15.pdf

HPEVS do mostly EV car kits but they make an oil-cooling system as an option for marine applications. They are based in USA and have alot of support and technical guides to help with the setup. They seem like a good-bet at a reasonable price from what is out there

Battery - LiFePo4 cells 3.2V 202Ah put 45 in series = 144V per 30kW pack. Cost is 75USD per cell or 3,300USD per pack. Parallel 6 to 9 packs to make a 180 to 260kW bank.

These cells can be purchased from China and assembled in the hulls to best suit the internal space that is available. Buying the batteries pre-assembled would mean having to find space for several large black boxes when compared to the size of the cells.

BMS - use a master / slave BMS solution.

Regards
Arran.

[barryglewis]

Can you clarify?
The controller (couldn't find it's details on their web page) converts the DC from the batteries into AC?.
How does the regeneration work?