Replace Diesel with electric engine

[Scaramanga F25]

Just not for your intended usage. Tried in a few catamarans and the power lasts only a few hours with a lot of solar panels in the Carribean.

[CarinaPDX]

Many hope for a "green" electric propulsion system, but it just isn't there. Solar panels, at this stage of development, put out too little power to be a practical source of propulsion power. Ultimately the owners I have met admit that they mostly run their genset when they need propulsion - which is less efficient due to conversion inefficiencies than a direct diesel drive. If all you did was motor in/out of marinas under power it might work - at a very high cost - but when talking about going anywhere under power it just doesn't pencil out.

Remember that most sailboats have more powerful diesels than is needed for cruising in calm water, a pretty low bar. They are sized to allow the boat to overcome wind and waves in all but very adverse conditions. You need to size the system for that application, and that rate of power conversion, in which case the solar panels are not doing much. I started out with an 18hp engine on Carina, an 11 ton boat, because it was just an "auxiliary" not a motor-sailor. Wrong. I have spent too many miserable hours trying to get into port against the weather making less than 1 knot over the bottom. You absolutely need substantial sustained power. Which means that the generator needs to be able to produce as much power as the diesel drive, and of course the motor needs to be capable of that kind of output. And then you have a far more complex (and hence less reliable) system at a very large price increase, with a large weight increase. And when it comes time to replace the battery bank the cost of a diesel overhaul (which you will have to do anyway with the genset) will seem minor.

Just off the top of my head I can think of two owners that went electric, and neither would do it again. One bought an electric cat with a giant array of soar panels - they were still having to run the genset most of the time. The other was a small traditional boat with solar panels and a very large number of lithium batteries; they used the batteries for short distances but still had to power up the genset for any distance.

Work out the realistic range of power needs, propulsion and house, and the realistic 24/7 output of the solar panels in all conditions, and I think you will find that the genset will need to produce the great bulk of the power - no win there.

Greg

[Taipe]

Several years ago I did the figures for converting, thinking that if large ships can run diesel-electric, why can't I do the same in my Tayana 37? It's a great idea to do away with rusted heat exchangers and reduce the number of parts, but unfortunately all-electric (or hybrid) would work only if your cruising is within about 30 minutes of a power grid for recharging (that means 60 minutes round trip). For serious cruising, even if the cost of the requirement for increased ampere storage from the batteries were not a limiting factor, the weight and limited space of the batteries w/ or w/o a genset would seriously interfere with sailing performance and would require at least a week of cloudless days within 20 degrees of the equator plus a half dozen wind generators to keep the battery bank charged.



Ships are designed to carry payloads, yachts are not. There is however good reason to hope that in the near future, current battery technology will bring considerable advantages in a welcome reduction of space and weight of batteries in proportion to amps of storage. But, I'm not holding my breath. Nor, would I be prepared to meet the expense until the price would drop years later to a competitive level with the current technology (no pun intended ...at least not consciously anyhow, hee, hee).



Many years ago, when my antique 2-stroke museum relic petrol-powered Stuart-Turner gave up on me, I sailed my 8 meter Scandinavian Folkboat in the Windward Islands of the Lesser Antilles. The tradewinds out of the northeast were nearly always consistent and I had no need for a motor, even in the tightest anchorages. There was only 5'4" of headroom, but I still long for the tranquility and performance of that lovely sloop! - All the very best to you!! /)~~~

[kirklkjb]

You may want to scale down your installation to enable you to get rid of your generator and use your diesel engine to charge a Li based battery system quickly. This is an intermediate step and could provide you power to run all systems for extended periods without running anything other than an inverter.

[Adelie]

Originally Posted by ArmyDaveNY

I am not familiar with the Amel, but I suggest you check out The Rigging Doctor on YouTube. They have an electric motor on their mid thirties foot mono. He has some good insights on it. They also have a regen. His battery bank is no where near as large as yours.

They are very happy with their set up but they are also very conscious of its limitations and are happy to live with those. In particular, they primarily use it simply to get in and out of marinas.

Good luck with what ever you decide upon.

Wisdom is a Morgan 45. 25,000 lb displ, 31' lwl.
Super Maramu is 35,275 lb.,, 41' lwl; so 40% heavier but on a 30% longer waterline.

Power requirements should be slightly higher for the same speed thru the water as Wisdom

https://sailboatdata.com/sailboat/morgan-45
https://sailboatdata.com/sailboat/super-maramu-amel

[ramblinrod]

I like YouTube's "Sailing Uma"'s explanation, "Our electric propulsion system is not a replacement for a diesel engine; it is a replacement for a sculling oar."

[Brewgyver]

Norbu09, In your notes you mention the Amel C drive, stating that it needed to remain, "bet may reduce the efficiency and regen capability a bit."

I would think it would be more like "eliminate any regen possibility."

There are other threads here on CF that go into regen in some depth, you may want to research those. The basic things to remember are
1. A propeller that is good at propulsion sucks at regen, and vice versa.
2. Going through that drive, with what amounts to two right angle gearboxes, adds a lot of friction.

[ArmyDaveNY]

Earlier I recommended the Rigging Doctor and here is the link where they discuss their particular experiences. Adelie earlier mentions some differences between their boat and yours, but this video is a pretty good discussion about what to expect. Again, they like it but they are aware of its limitations. In particular one of the big limitations is that you really cannot effectively go through the ICW, extended canal systems, etc. It is great for ocean sailing though.

They talk about speeds required in order to use regen, prop size, advantages and disadvantages, noise, etc. Here is the link.

https://www.youtube.com/watch?v=QWgbM9DoA7A

What are your reasons for considering, and goals for, an electric system? If you include those, perhaps many can address those with a little more precision. Right now we're talking in generalities.

[s/v Jedi]

So I have two remarks about the schematics:

1. Battery bank parallel string loading. This needs to be fixed, is easy. The bottom string is favored over all other ones and the top string is the least favorite. The resistance for each parallel path need to be equal. The simplest way of doing that is to move the main negative cable from bottom left to top left, or the main positive from bottom right to top right. Follow the path through each parallel string to verify equal length.

2. I recommend a bit more elaborate implementation of the input section around shore power, genset and inverter/charger. Also, I recommend to not use the second input of the Quattro (even get a cheaper Multiplus if available for your voltages). See the attached diagram, which is for our setup but you can find the relevant parts. First note that the input breakers include A/C, water heater as well as one labeled “bypass”. It is used to bypass inverter/charger(s) in case of trouble. The idea with A/C and water heater is that they only get powered from genset or shore power so keep those loads away from inverters etc.
Last is the groups created after the inverter/charger(s). This allows loads to be spread over different sources incl. Bypass.
This setup, if two inverter/chargers are used, allows shore power frequency conversion. To do this, only enable the input breaker of one inverter/charger, which will start charging the battery bank. The other unit will invert and you choose that as the source with the group rotary switches.

[seandepagnier]

Wow, a lot of negative remarks against electric that do not help or answer the OP's questions.

People end up on rocks because of poor navigation not because of lack of engine power. Many risks are taken because of the engine and trusting electronic navigation systems too much.

Originally Posted by Woodland Hills

sufficient to keep you off of a lee shore in a blow when your anchor drags at night?

Originally Posted by skipmac

entering a new marina to find a 3 kt current pushing me sideways into a megayacht.

Been in these scenarios and worse and always managed to avert danger using sail alone. A lot of boats lost because the owner tried to use the engine rather than raise the sail.

5-8 hours under power ..... For most cruising 5-8 hours should be fine but would not work for cruising the canals of Europe or the US ICW.

For the US ICW. You do not need any power besides sail. An electric motor may be convenient but not required.

5. Cost. Once you add batteries, charging systems, controls, etc electric can cost double or triple the cost of a new diesel engine.

Since there is a propeller shaft in the boat with nothing attached, I'm putting in an electric drive for fun to see what it can do. I already have all the parts. The motor cost $50 (free shipping) is 2800 watt brushless motor with rare earth magnets. The gear reduction using chain and belt (2 stage) This cost $30 in total because you can 3d print the pulleys. The controller cost $23 on ebay, and it uses 24 volt 40ah lithium iron battery cost $600. Will be interesting to see the performance, it is likely 3-4 knots speed and 10-12 miles going slowly with 250 watts solar to recharge.

Originally Posted by ramblinrod

Remember that there is nothing "green" about electric propulsion, as the electrical energy used to power is likely produced mostly by coal, deisel, or nuclear.

You can choose how you generate the energy to charge your batteries.

Originally Posted by Brewgyver

research those. The basic things to remember are
1. A propeller that is good at propulsion sucks at regen, and vice versa.
2. Going through that drive, with what amounts to two right angle gearboxes, adds a lot of friction.

Very good points. I suggest the OP look into dedicated hydro-gen or tow gen rather than regen for about twice the power for the same drag. This will have a repeller which is the inverse of a propellor. You can't just flip it around unless you were a 4th dimensional being.

I 3d printed a repeller that is 16 inches diameter and glassed over it, it produces half an amp in tidal current at anchor in charleston which has only a 2 knot current. Normally impossible to generate any power from this speed of current with a propeller.


As for friction it is critical. Most diesel designs do not consider efficiency as a primary objective and it is questionable if you should use existing propellers drive trains or sail drives unless you want to sacrifice large losses.

Most cruising boats have less than 20% efficiency from shaft to propulsion due to a small diameter propeller (<2ft) torqueedo claims 54% efficiency but this is a best case not usually achieved. Specially designed solar boats can achieve 80% or better. A well designed wooden sculling oar is around 85% efficient.

Originally Posted by nwdiver

you have the diesel when absolutely necessary.

ie: never

Originally Posted by roverhi

Electric is great for those not going anywhere.

Diesel is ok by me if you never use it.

[lordgeoff]

Originally Posted by norbu09

Hi, I am new here, please let me know if I post in the wrong spot or make any other rooky mistakes

We live on an Amel Super Maramu in La Rochelle, France and work through our refit at the moment. We planned to go cruising soon but the diesel died so we are now looking at an electric conversion. We did toss many ideas around and landed on a system that I hope is easy to work on, easy to find parts for and good enough to get some first experience. Then, over the coming year, we plan to build out the system so it is fit to sail us home from France to New Zealand.

The system is built around a 48V Lithium battery bank that will service the boat needs and the engine. I have some initial drawings around the idea and would love to get feedback from those who have built systems like this.



The drive system will most likely be a oceanvolt AXC which runs on 48V.

The plan for the battery bank looks like this at the moment:



cheers
Lenz

If you are doing ocean crossings like the coconut run to NZ then you need to be prepared for all eventualities. Using an electric motor /batteries and solar panels (at great great great expense) you are doing the equivalent of carrying probably about 50Lt diesel and using a Diesel engine.
Yes there are trade winds and that should mean you can predominantly sail.
Be prepared to motor a lot however. Sometimes for days at a time.
Suggest putting Head before Heart.
Fossil Fuel transportation is just so damn reliable, cheap and you can carry and store enormous amounts of energy that is used efficiently via a Diesel engine.
Head before Heart.

[norbu09]

Originally Posted by s/v Jedi

So I have two remarks about the schematics:

1. Battery bank parallel string loading. This needs to be fixed, is easy. The bottom string is favored over all other ones and the top string is the least favorite. The resistance for each parallel path need to be equal. The simplest way of doing that is to move the main negative cable from bottom left to top left, or the main positive from bottom right to top right. Follow the path through each parallel string to verify equal length.

Awesome, thanks will look into that today and post an update based on this and other feedback I got elsewhere.

Originally Posted by s/v Jedi

2. I recommend a bit more elaborate implementation of the input section around shore power, genset and inverter/charger. Also, I recommend to not use the second input of the Quattro (even get a cheaper Multiplus if available for your voltages). See the attached diagram, which is for our setup but you can find the relevant parts. First note that the input breakers include A/C, water heater as well as one labeled “bypass”. It is used to bypass inverter/charger(s) in case of trouble. The idea with A/C and water heater is that they only get powered from genset or shore power so keep those loads away from inverters etc.
Last is the groups created after the inverter/charger(s). This allows loads to be spread over different sources incl. Bypass.
This setup, if two inverter/chargers are used, allows shore power frequency conversion. To do this, only enable the input breaker of one inverter/charger, which will start charging the battery bank. The other unit will invert and you choose that as the source with the group rotary switches.

Interesting point. I'll think about that, it is more gear but maybe cheaper gear and adds redundancy. Thanks for that

[norbu09]

Thanks everyone for your insights and the worries everyone shares about us and our travels.
In terms of regen, Amel has put an alternator sitting on the prop shaft for generating electricity factory sides already. The Prop is a MaxProp that can "push" and "pull" and the setup is working pretty well under sail from around 5 knots onward. Based on that we think that the electric engine should work well on regen too, may need higher speeds though.

[skipmac]

Originally Posted by boat_alexandra

People end up on rocks because of poor navigation not because of lack of engine power.

Boats end up on the rocks for many different reasons.
Certainly poor navigation is a common cause but can also happen from dragging anchor. Also, depending on the boat and conditions it's not always possible to sail off a lee shore.

Many risks are taken because of the engine and trusting electronic navigation systems too much.

On this I completely agree.

boat_alexandra Been in these scenarios and worse and always managed to avert danger using sail alone. A lot of boats lost because the owner tried to use the engine rather than raise the sail.

Regarding sail power in a marina scenario that is very often not possible. Most of the docks and marinas I stop at are in protected areas like far inside a harbor, sometimes inland on a river. Some of the harbors are surrounded by high hills which can block winds altogether or result in winds that are light, extremely variable and unreliable. In the situation I mentioned there was little wind at all.

For the US ICW. You do not need any power besides sail. An electric motor may be convenient but not required.

Same comments. Many sections of the ICW are inland and often have little wind or variable winds. Yes it is possible to sail the ICW but unless one has unlimited time to wait for the right conditions not very practical. Also long sections of the ICW are very narrow and would not be very safe to sail, certainly no room to tack if the winds were not perfectly favorable.

Further, it is not legal to sail through many of the opening bridges and I know of some that will not open until you drop your sails. Also not safe to sail under bridges, opening or fixed as the winds often change direction dramatically as it funnels under the bridge or is blocked altogether.

For a smaller boat that you can fend off or scull all this may be possible but for a larger boat, not at all practical nor safe.

[jackheape]

There is a group on Yahoo devoted to electric boats. Lot so fgood info and insights on there, plus there is at least one professional electric system installer who shares his knowledge. I joined when I was thinking about electric conversion. I ultimately decided against it.