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Old 08-16-2017, 01:36 PM   #1
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Hybrid electric drive

Hello everybody, i don't own a boat yet but some friends of mine are pushing me to buy my own and enjoy summer with them. I've read some post about repowering from diesel engine to electric. What are your thoughts about using the parts from a chevy Volt, battery pack, engine and generator.

These parts are pretty cheap at a salvage yard. The electric motor ( 11 Kw ) is sufficient to move a 3800 pounds car at hwy speed, i know that a trawler is way more heavier than this, but all it has to do is spin the props... Generator is rated at 50 Kw or so making it big enough to drive the electric motor when the battery pack comes too weak and even recharge it.

I'm looking for a 30-40' trawler with a dead or old engine. It could be a way to cut the operating cost of the trawler since that engine runs on fumes and solar panels + windmill could help with the battery recharge. What do you think ? Thank's for your insights.
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Old 08-16-2017, 02:06 PM   #2
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Not ready for prime time just yet, just not as efficient or effective as s diesel

Except within a very narrow performance window
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Old 08-16-2017, 02:47 PM   #3
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Interesting subject, impatient to see the comments

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Old 08-16-2017, 02:58 PM   #4
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Originally Posted by lpedleur View Post
Hello everybody, i don't own a boat yet but some friends of mine are pushing me to buy my own and enjoy summer with them. I've read some post about repowering from diesel engine to electric.

Welcome aboard.

If it helps, there are several threads here and on cruisersforum.com (sister site) about electric drives of various sorts. You could do a search on those and find discussions about pros/cons, hurdles and impediments, etc.

The short version seems to be they could work, in specific boats for specific missions under specific circumstances... but that for any sort of long-ish distances there are are several extra issues to consider at the same time (battery type/chemistry, solar and/or wind-generator augmentation, charge controllers and battery management systems, sail augmentation, etc.

There are also discussions about the green-ness (?) or lack thereof, one thread being about how electric propulsion mostly shifts original pollution sources away from the end-user back to some electricity producers... but maybe doesn't really reduce or eliminate whole-earth greenhouse gasses and etc. very much (some would say, if any).

Note that cars can coast, and regenerate electricity. Much heavier powerboats (your example) never really coast over distances, and powerboats can't really regenerate (as perhaps a sailing vessel could under certain circumstances).

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Old 08-16-2017, 03:16 PM   #5
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Actually, I haven't yet seen any discussion on using an electric car drivetrain to repower a boat. Perhaps it could even make financial sense. (although that is rare for any boat project)

When I looked at options for re-powering my boat and replacing the fuel tanks, I considered going electric. The total cost of parts for the conversion (motor, batteries, charging system) was $32,000 A new diesel engine plus new fuel tanks was $14,000. I'm still filling up with diesel.
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Old 08-16-2017, 06:45 PM   #6
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Actually, I haven't yet seen any discussion on using an electric car drivetrain to repower a boat. Perhaps it could even make financial sense. (although that is rare for any boat project)

When I looked at options for re-powering my boat and replacing the fuel tanks, I considered going electric. The total cost of parts for the conversion (motor, batteries, charging system) was $32,000 A new diesel engine plus new fuel tanks was $14,000. I'm still filling up with diesel.
Wow 32K... in my non engineer head, i would have used a wrecked Volt, they sell for around 8000$ (assuming that the parts needed are still ok) and just add labor. But as you said, it may be cheaper to put diesel in it.
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Old 08-16-2017, 07:17 PM   #7
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PassageMaker Magazine had several articles about diesel over electric some time back. A company installed electric motors in a trawler with diesel generators. It looked good, but the idea seemed to die. It was not cheaper than diesel engines if I remember. The torque from a properly sized electrie motor is incredible at very low RPMs. That facilitated low speed handling.
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Old 08-16-2017, 08:59 PM   #8
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The problem with diesel electric (diesel engine drives generator, generator powers electric motor that drives prop) is that right from the get go, you have a 20% or so power loss compared to a diesel directly driving a prop. That's because the generator has power losses, and the electric motor has losses. If you also charge and then discharge a battery, you lose another 10% or so. These are rough numbers, but not too far off, and serve to make the point.

Given this, you might ask why anyone would ever consider hybrid propulsion, and it is indeed a good question. The physics just don't support it in any way.

The simplistic, and incorrect argument is that if a hybrid is more efficient in a car, it must also be more efficient in a boat. This leap of logic fails to recognize WHY a hybrid works well in a car. A car's engine puts out a bunch of energy to bring the car up to speed, converting the engine energy into momentum of the car. But then the car mostly glides and much less energy is required to maintain speed. When you put on the brakes and stop the car, all the energy in the car's momentum is turned into heat by the breaks and thrown away. With a hybrid, the car is slowed down by placing a generator load on the wheels and instead of turning all the stored momentum energy into heat, a big chunk of it gets turned back into electric power stored in the battery and usable again later own.

None of this happens with a boat. It takes a constant, large amount of energy to move the boat. There is little to no stored momentum energy, and water friction stops the boat in short order when you remove the engine power. There is no energy to recover since it's all taken by the sea.

One argument in favor of a hybrid system is that it lets you run the diesel at it's most efficient power point. This might be possible, and could run the engine at perhaps 15% better fuel efficiency. With that, you might be back to break even, but most likely you will still be running at reduced efficiency compared to direct drive.


People also point at large cruise ships and tugs that have diesel electric drives as proof of efficiency. But it isn't really. In these applications the diesel electric provides more of a benefit as a transmission than efficiency. It's the same reason why diesel electric is favored for train locomotives.

But for boats, it really doesn't make any sense.
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Old 08-16-2017, 09:27 PM   #9
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A Chevy weights in at just over 3000lbs, a 40' trawler weights in at well over 30000lbs.
that Chevy power-train will have a very hard time just getting the trawler to move.
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Old 08-16-2017, 09:32 PM   #10
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It's the same reason why diesel electric is favored for train locomotives.

But for boats, it really doesn't make any sense.
In the past when a loco was breaking the energy from breaking was transformed in electric power that was "burnt" using resistors. They were calling these "toaster" as i was really like a toaster on top of the loco and if by any luck a bird was there it would have been grilled in few seconds.
Nowadays this energy is put back in batteries for reuse instead of being just burnt.

I may be wrong but the benefit of diesel electric is more for long runs where the engine will always run at optimal rpm for a long period of time, what is the trawler type of usage. With this setup you do not run an engine for the screw but you provide electric energy that is used for propulsion as well as onboard systems.
The point (I think) is that, even if you have some lost in energy transformation between thermal to electric to mechanic, usually engine power required to produce power is less than engine power required to direct turn your screw.

But hey I am not an expert

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Old 08-16-2017, 09:38 PM   #11
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I think Twistedtree nailed it.

I would add that fuel cost is one of the least significant expenses of boat ownership and operation for most of us. (Mores the pity.)
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Old 08-16-2017, 09:53 PM   #12
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But for boats, it really doesn't make any sense.
It doesn't make sense if the only consideration is saving money.

But consider a boat with a bunch of solar, a bunch of LiPO batteries, and a parallel hybrid system:

Household appliances with no worries about electric usage
No generator necessary
No shore power necessary
Redundancy (get home on solar)
Charge the batteries (when solar doesn't get it done) in a short time
Quiet and fume-free when using electric propulsion (canals)
Lots of torque at 1 rpm using electric propulsion (docking)
Diesel power when you need it

Does it save money? Who cares.
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Old 08-16-2017, 10:26 PM   #13
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A Chevy weights in at just over 3000lbs, a 40' trawler weights in at well over 30000lbs.
that Chevy power-train will have a very hard time just getting the trawler to move.
The Volt electric motors produce about 150 hp and 270 ft-lbs of torque. That should get it done.
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Old 08-17-2017, 05:07 AM   #14
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The Volt has a gasoline engine. Gasoline fumes are potentially explosive, so you would need spark proof elec equipment, and extra engine room ventilation.
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Old 08-17-2017, 05:17 AM   #15
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Putting the money aspect aside several years ago. , most diesel electric concepts involve quite a bit more complexity and components than a conventional diesel drive. I understand wanting to be "green" or out front with technology, but then reality raises head.

There is a magazine and 2 shows a year dedicated to Hybrid Propulsion. Its a trade show and all the companies involved in the emerging technology are there as well as many technical presentations by some pretty smart people. Europe is way ahead of the US in this technology, they also have much higher fuel costs and the performance envelope of many of their vessels fit in the narrow range where the current technology works.

Home | Electric & Hybrid Marine World Expo 2018

There are also several boat manufacturers that are making hybrid boats. Greenline in Europe, Elco and Duffy here in the US. There have also been several experiments by production builders like the Lagoon Sailing Catamarans several years ago. This technology actually makes more sense for a sailboat than a powerboat at this time. I believe all but one of the experimental Lagoons was repowered conventional.

https://www.greenlinehybridusa.com/n...0-hybrid-info/

You can buy, make, develop, cobble together a Hybrid drive trawler, but the only upside at this time in technology development seems to be bragging rights. Range, speed, complexity, cost, maintenance, etc. are all reasons not to.......just yet.




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It doesn't make sense if the only consideration is saving money.

But consider a boat with a bunch of solar, a bunch of LiPO batteries, and a parallel hybrid system:

Household appliances with no worries about electric usage
No generator necessary
No shore power necessary
Redundancy (get home on solar)
Charge the batteries (when solar doesn't get it done) in a short time
Quiet and fume-free when using electric propulsion (canals)
Lots of torque at 1 rpm using electric propulsion (docking)
Diesel power when you need it

Does it save money? Who cares.
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Old 08-17-2017, 05:37 AM   #16
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There used to be a TF poster named Rueben Trane of Florida Bay Coaster fame and also president of Island Pilot. One day he set out to build a hybrid electric drive boat called the called the 2009 DSE 12M Hybrid that was literally covered with 6KW of solar panels. Through batteries and solar panels, she would do 25NM per day on electric power. She was powered by two Steyr 75HP/7KW diesel/electric hybrid engines.

I first came across the boat about 4 years ago on Yachtworld as it was for sale and may have been for sale for some time. Today, it is still for sale. The point here is buyers haven't been swept off their feet by electric boats and if you do this conversion, you may have a hard time getting rid of it when the day comes.

If you want to view the boat, go to YW and do a search on Island Pilot.
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Old 08-17-2017, 05:52 AM   #17
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There have also been several experiments by production builders like the Lagoon Sailing Catamarans several years ago. This technology actually makes more sense for a sailboat than a powerboat at this time. I believe all but one of the experimental Lagoons was repowered conventional.


You can buy, make, develop, cobble together a Hybrid drive trawler, but the only upside at this time in technology development seems to be bragging rights. Range, speed, complexity, cost, maintenance, etc. are all reasons not to.......just yet.

The Lagoon 420 was an unmitigated disaster! Yes, they were basically all retrofitted with diesel drive systems. Unfortunately. I tried finding one with the electric systems only. my plan was to fit a proper diesel in one hull to shaft drive a prop, but also have a generator on it that would drive the electric motor driven prop in the second hull. A cat with just one diesel would be a plus. A lot of cat sailors just run one engine, but that is not ideal.

I had a dock neighbour with a Lagoon 420 a couple or years ago, and his view was 'the drive system is perfect, the problem is the charging system'. He wasn't a tech kinda guy, just didn't get it. Even with oversized gennies for a sailboat (18kw or more) it just wasn't gonna cut the mustard. Even for a sailing boat of modest size battery capacity is way short of what is required for anything apart from harbour manoeuvres and docking. I still struggle to believe Lagoon actually advertised, produced and sold the things! I can'r imagine that the engineers involved are still employed by Lagoon!

Hybrid boats that work at present are day/picnic boats for rivers and small lakes. Nothing wrong with that.
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Old 08-17-2017, 06:24 AM   #18
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There are also several boat manufacturers that are making hybrid boats. Greenline in Europe, Elco and Duffy here in the US. There have also been several experiments by production builders like the Lagoon Sailing Catamarans several years ago. This technology actually makes more sense for a sailboat than a powerboat at this time. I believe all but one of the experimental Lagoons was repowered conventional.

Greenline claims to have built hundreds of boats. How many have the full electric propulsion package is not clear, but most of the used boats available on Yachtworld, for instance, seem to have it.
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Old 08-17-2017, 10:18 AM   #19
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I was trying to be polite



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The Lagoon 420 was an unmitigated disaster! Yes, they were basically all retrofitted with diesel drive systems. .
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Old 08-17-2017, 02:11 PM   #20
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In the past when a loco was breaking the energy from breaking was transformed in electric power that was "burnt" using resistors. They were calling these "toaster" as i was really like a toaster on top of the loco and if by any luck a bird was there it would have been grilled in few seconds.
Nowadays this energy is put back in batteries for reuse instead of being just burnt.
Those are also referred to as Dynamic Brakes

Quote:
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The point (I think) is that, even if you have some lost in energy transformation between thermal to electric to mechanic, usually engine power required to produce power is less than engine power required to direct turn your screw.

But hey I am not an expert

L.
But that's exactly the point. It will always take more diesel power to turn the same screw the same speed with a diesel electric as compared to direct drive. It's a basic law of physics.
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