Combi electric motor hybrid experience

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mattonthesea

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Sailing Uma interviewed Combi this week including a bit about their diesel hybrid conversion. Looks like it ticks all the boxes for someone who likes the idea of electric but the expense and downsides are too much, or too many workarounds.

Their website is lacking in information so wondering if anyone here has experience of converting to hybrid?
 
There are two generic types of electric hybrid drive
- serial hybrid - an electric drive with a diesel (or fuel cell) generator as a “range extender”
- parallel hybrid - with both diesel and electric motors which can be used.

Not sure what type was being referred to on the Uma video?

However, a serial hybrid is a seriously attractive option for a new build boat (albeit not necessarily cheap). Was chatting to the very happy owner of a modern fast cruising yacht who has gone the serial hybrid route.

Not sure the parallel hybrid option is so attractive, unless some very specific needs.
 
Doubt you will find much real life experience as the concept is a bit of a blind alley for yacht auxiliaries unless on new build or conversion on largish yachts that have heavy use electrical systems. Expensive and bulky but have advantages over separate engines and generators, particularly a high level of usage is expected.
 
The Bristol Channel Pilot Cutter Mascotte (originally from 1904) has what you might call a serial hybrid but uses hydraulics rather than electrics. This allows a single engine to drive both propellors and allows the engine to be placed a convenient location without having to change the position of the original companionway steps etc. The two propellors makes maneuvering the boat so much easier.

A pilot cutter with a single prop is unsteerable in reverse.

I would have thought that serial hybrids would be interesting for many kinds of boats as a podded drive could be used and only an electric cable needs to pass into the pod instead of a rotating shaft as in IPS drives making the seals so much cheaper and simpler.

The pods can also be placed in different locations from what would be done with a standard shaft drive or IPS drive system to optimize the water flow around the hull. The engine can then be placed anywhere in the boat improving the use of space inside the boat and having better access to the engine for maintenance.

I would have thought that a serial hybrid has a lot of advantages and I am surprised that we do not see much development in this space.

Note that all modern cruise ships are serial hybrids.

I see no point in parallel hybrids. That would seem to unite all the disadvantages of both systems without gaining much.
 
westernman said:
The Bristol Channel Pilot Cutter Mascotte (originally from 1904) has what you might call a serial hybrid but uses hydraulics rather than electrics. This allows a single engine to drive both propellors and allows the engine to be placed a convenient location without having to change the position of the original companionway steps etc. The two propellors makes maneuvering the boat so much easier.

A pilot cutter with a single prop is unsteerable in reverse.

I would have thought that serial hybrids would be interesting for many kinds of boats as a podded drive could be used and only an electric cable needs to pass into the pod instead of a rotating shaft as in IPS drives making the seals so much cheaper and simpler.

The pods can also be placed in different locations from what would be done with a standard shaft drive or IPS drive system to optimize the water flow around the hull. The engine can then be placed anywhere in the boat improving the use of space inside the boat and having better access to the engine for maintenance.

I would have thought that a serial hybrid has a lot of advantages and I am surprised that we do not see much development in this space.

Note that all modern cruise ships are serial hybrids.

I see no point in parallel hybrids. That would seem to unite all the disadvantages of both systems without gaining much.
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Agree about the parallel hybrids.
But a "serial hybrid" electric drive is generally meant to cover vessels which can progress in pure battery EV mode for a reasonable period without the generator running.
I am not aware of any ocean going cruise ships that can run in battery EV mode. They are more like the old diesel electric BR trains.
 
As usual I was not specific enough in my question. I was referring specifically to the Combi bolt-on conversion. They have versions for most engines. They slip a pulley or similar on the shaft and a motor/alternator drives, or is driven, by that via a belt. The idea being that you don't have to ditch your present engine.
 
mattonthesea said:
As usual I was not specific enough in my question. I was referring specifically to the Combi bolt-on conversion. They have versions for most engines. They slip a pulley or similar on the shaft and a motor/alternator drives, or is driven, by that via a belt. The idea being that you don't have to ditch your present engine.
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Hybrid Marine are the guys if you want a parallel hybrid - Home
 
Neeves said:
Focussing more on sail - there is surely a place for hydro generators, either using a pod, see Post 4, or something like a WattnSea - or both.

Jonathan
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This is surely the way things have to go, at least for displacement sail boats. Once you’ve got to hull speed, you’d lose very little by taking some energy back.
 
mattonthesea said:
As usual I was not specific enough in my question. I was referring specifically to the Combi bolt-on conversion. They have versions for most engines. They slip a pulley or similar on the shaft and a motor/alternator drives, or is driven, by that via a belt. The idea being that you don't have to ditch your present engine.
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Lot of unanswered questions there, Just adding a generator onto an existing engine is only one piece of the jigsaw and suspect that once you build a system to take advantage of the generator capacity the cost would be high. Also electric only propulsion is likely to be very limited as it will depend on energy storage capacity. Suspect that the market for this sort of compromise is likely to be very limited, but guess it depends on what you are trying to achieve.
 
mattonthesea said:
As usual I was not specific enough in my question. I was referring specifically to the Combi bolt-on conversion. They have versions for most engines. They slip a pulley or similar on the shaft and a motor/alternator drives, or is driven, by that via a belt. The idea being that you don't have to ditch your present engine.
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I think it’s a good idea. Not all that different to what one of the YouTube channels recently fitted (maybe MJ or Ruby Rose). It’s effectively just a massive alternator that can be driven for propulsion and a clutch allowing either diesel or electric power. I think many boats will lack the space where needed but for those that don’t it’ll be a great solution for shaft drives.
 
mattonthesea said:
Yes but that is from scratch. I am asking if anyone has experience of retro fit 🙂
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I suspect it is extremely difficult to make a plausible case for retro fit of any electric engine (hybrid or otherwise), unless the existing diesel is scrap - and hence effectively a new fit anyway.
Don’t forget that it is likely that Sailing Uma had a LOT of financial assistance from OceanVolt for their electric drive - now on at least iteration 3.
 
Neeves said:
Focussing more on sail - there is surely a place for hydro generators, either using a pod, see Post 4, or something like a WattnSea - or both.

Jonathan
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Hydro generators like WattnSea are already pretty much standard equipment for boats doing blue water sailing - eg ARC. And work very well for power generation under sail, particularly on boats that can average 7-8 knots.

But of zero relevance to a thread of electric propulsion. Any decent electric drive configuration will be designed to provide hydro generation under sail. Hence no need for a separate hydro generator.
This is one of the factors that starts to make a serial hybrid a viable economic proposition for a new build blue water sailor - which would otherwise typically have a diesel main engine, diesel generator and WattnSea hydro generator.
BUT the optimum prop geometry for regeneration is different from propulsion, and also want a feathering/folding low drag mode. Hence why things like the specialised OceanVolt drives with fancy propellor feathering technology.
 
dunedin said:
I suspect it is extremely difficult to make a plausible case for retro fit of any electric engine (hybrid or otherwise), unless the existing diesel is scrap - and hence effectively a new fit anyway
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Very much disagree. Even a lot of the new ones have the “massive alternator” type arrangement which would be almost trivial to fit if there’s room. This gives you huge regen, silent running for first and last mile, and allows you to keep the existing working diesel in place. Best of all worlds with minimal compromise, especially if upgrading the batteries anyway.
 
lustyd said:
Very much disagree. Even a lot of the new ones have the “massive alternator” type arrangement which would be almost trivial to fit if there’s room. This gives you huge regen, silent running for first and last mile, and allows you to keep the existing working diesel in place. Best of all worlds with minimal compromise, especially if upgrading the batteries anyway.
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Have you actually listened to the clip in the video? he was very vague on what it will actually do and there is no information on their site. There seems to be an automatic assumption that "electric is good" but there are big unanswered questions about what "problem" this kind of set up will actually solve and is it economically viable. Just as an example as you have raised it can you explain why being able to run for short periods at low speed using electric when entering and leaving harbour is an advantage? How big a battery bank do you need to absorb the output of a 6kw generator on a small(ish) boat that might use a 30hp engine that the demo set up was fitted to? And what else are you running on the boat that needs such a high potential supply of energy?
 
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