Electric Boat Conversion With Generator

by Tim

I want to convert my 30 ft. boat's V8 gas-guzzlers to 2 DC electric motors that run with a 10KW generator. I'm going to have batteries for running lights, bilge pumps etc., but I want to run the motors with a generator only. What would I need?

Hi, Tim -
I think you're asking a lot from a 10 KW generator.

If you've got more than one big V8 engine powering your boat, you can figure on one big DC motor (A NetGain TransWarp 11 or 13?) with its own big (30-40kw? More?) generator to give you the same kind of power.

In a car, the size of the generator is really dependent on how much acceleration you need, because that's where you burn the energy. The boat is pretty much the same, I think. You need the most energy to take off, then less after you reach cruising speed. Right?
The trouble here is that if you don't have any storage batteries, you need a larger generator to provide enough power for acceleration.

You didn't say why you don't want to use batteries to run your motors, but I guess you've got a good reason.
Me, I'd prefer a battery pack to a bigger generator.

Good luck with your project, Tim!


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marine applications
by: robin

HiI am also workingon a conversion with a 53 ft cruiser twin diesel and hoping to retain the currant reverse gears,sorry i hope im in the spot to ask this help or thoughts helpful ,cheers

I have searay 340 want to convert to elect
by: Troy T

I have a 340 searay I want to convert to fully electric or Diesel Hybrid its running twin 7.4 Mercs at this time with v drives

has anyone converted something this big I want to maintain the ability to run on plane at the same speeds

What kind of power would I be looking at to run batteries and or diesel hybrid to both props

Tesla Battery Speed Boat
by: Anonymous

I converted my 2006 Bayliner 175 to All Electric.>



Where to start
by: Snowy

Have displacement hull, so weight is not a problem. Want to replace a 50 hp diesel @ 2200 rpm to electric. Need 6 hour duration including reserve. Where to start...
A. Is it possible
B. Using how many 8d 1800 cc batteries ...or ?
C. What type of motor.
D. Currently has Borg Warner silk gear box, shifting in the 300-500 rpm range.

What say all you guru's out there. Is it possible?

Electric boats have arrived
by: Anonymous

Check out this link these are some guys that did an electric retrofit of a 30 ft cabin cruiser.


The motors and controller came from Clean E Marine.

You are better of removing the 460's and the gas tanks that will take off about 1500lbs.

Very interesting.
by: Patrick

I also have a 30' boat primarily used for fishing.
The last two weeks I have been researching different propulsion systems and I believe electric would be the best way to go. Unfortunately, I need to get on plane and most of the systems that I have found are more for sailboats.
I currently have twin 350s and plan to repower next year.

When you are getting .9 GPM Electric propulsion sounds really nice. Did I mention I like to offshore fish. Lol

A generator/batteries running twin electric motors is what I am looking for but, without compromising to much power.

hybrid boat makes so much sense
by: Anonymous

V8 marine engine weighs a lot, getting rid of it is a good idea :)

You can fit a lot of batteries and electric motor for the weight of the original motor.

Cars and bikes are very weight restricted, 30ft boat without a V8 motor is not, so you can use cheaper batteries.

With battery pack you can use smaller generator and burn less fuel.

You can charge batteries in port, and probably even fit a solar panel (if you have space) and cruise for free :)

Good luck!

Electric (commercial) Tritoon
by: Jay

I have a 26ft JC Craft Tritoon which is converted into a Concession Boat (basically a food truck on the water)
it is presently powered (significantly overpowered) by a V6 Mercruiser.
at this moment, I have a complete electric propulsion system based on a pair of 82lb thrust MOtorguide trolling motor lower units, Yandina Trollbridge24 and a bank of four 8D batteries charged by main gass guzzler or 5.5KW genset.
before fabricating the brackets/trim/Kort Nozzles, I stopped to do some further research, -simply put, I'd rather stop right here, sell off what I was ABOUT to use, and put together a pair of 8-15kw motors/drive/controller (and probably beef up the battery bank, or perhaps switch to larger diesel genset for a sort of diesel electric setup.
This boat will be operating 12hrs day 6 days week starting early-mid December, so if I am to do this, I need to do it NOW, and I am asking for the advice and suggestions of anyone in the know who is willing to help in any way.
it is my intent to operate under strictly electric propulsion, and to eventually eliminate the V6 -since a boat like this only needs to hit 4-7kts, and will normally only travel about 10miles/day.
the reason for two motors (port/starboart) is A. I want to steer with them, joystick controller, like a tracked vehicle, and B. because I have a huge amount of room in the stern of each outer hull, enough room for large enough electric motors to put this gal on plane, of course, that's not at all the plan/need...
with the 185hp V6 Mercruiser, she tops out at 31kts mostly empty and 25.5kts loaded, and this is with a commercial kitchen, and all affiliated systems (full fuel/water tanks)
now you know why I said "significantly overpowered, as a 26ft "house boat" like this has no business operating at those speeds..
again, any advice, suggestions or direction will be most gratefully appreciated!

Boat conversion
by: gs1807

I have a 30 ft boat and considering
A repower recently saw a
Commercial on TV a pick up truck hauling
A 35 ft aluminum boat I noticed the props
Were attached to what appeared as water proof
electric motors I belive that some large ships
Are designed in the same manner I don't no
Which DC or AC you probably don't need
A transmission it's cheeper to just reverse
The motors my idea would be to make up or
Get a pair of water proof motors throw
Away the lower outdrive units make up motor
Adapter brackets and mount electric waterproof
Motors to existing gimble and power with 40kw
Water cooled Diesel

by: Anonymous

This is a great forum.

I have a 32' Prairie Trawler, with displacement hull and lots of room for a battery bank.

I am putting together a go no go list for project viability. I have lots of questions to answer re engineering.

I thought with the extent of this it may be worth a discussion of its own, so we can all learn.

If I decide to go, I will be glad to share the journey.

Are we able to post pix as well?

Motor and Battery equals electric boat.
by: Anonymous


This video has disappeared...
I've converted my boat and built controller and LiFePo battery system for it.

link to photos of my hybrid cabin cruiser
by: imwoody36

here is a link to the installation process

we have one of the planned two prius drive trains installed into this 32 foot cabin cruiser.

float testing is planned for may 2013.

another hybrid boat repower project
by: imwoody36

I am repowering a cabin cruiser with a hybrid drive system from a Prius.
I have realistic expectations about speed.
( low) Our intended use is in lakes, and weekend camping onboard. I intend for the hybrid system to provide my climate control for the cabin, and also the 12 volt cabin power supply, I have the skills with the prius system to accomplish this.
my question to the forum is this:
when connecting the drive shaft from the toyota transmission to the mercruiser alpha outdrive,
does anyone have experience with automotive grade CV axles? specifically should I replace them with a heavy duty equivalent?
I welcome comments about the transmission mating in particular as my experience is with control systems

great idea
by: Anonymous

I think that electric boat is a great idea.

Already some are in production. we will have to comme up with some kind of hybride.

so you need a good water cooled electric motor.
a battery pack
a generator

I think that pontoon are great candidate for electric

I have a 21 ft starcraft islander that could also be a very good conversion platform because of its size and light weight.

What would you do
by: Phil

I also have a 30 foot cruiser and would like to look at electric power. I have twin 460 Ford's and I was thinking of putting in an electric motor in between these monsters so that I could put along 1 to 5 knots. Most of the time I'm not in a hurry and speed is not what I'm looking for.
I could put a shaft in between the two existing motors and the rest could go in front of the motors. I would say you have two feet of area in front of the engines that you could free up easily by moving the four batteries and hot water tank to another area on the boat.

Cars and Boats not equivalent
by: Roger

Unlike a car, which requires more energy to accelerate and less to cruise, a boat faces constant high drag due to water density. Drag when the boat is on a plane is somewhat reduced, but still much higher that the drag on a car at cruise. the most efficient speed for a boat is at hull speed, which for a 30' boat is around 6-7 knots (if i remember right). There is a mathematical formula for calculating hull speed. If you spend most of your boat time off plane, then you can use a smaller electric motor to replace the V8.

boat conversion gas to electric
by: Greg

Im thinking of buying a boat in the 35 ft range.
I would prefer diesel over gas but would eventually like elec. I can buy a 35 footer with twin gas engines cheap right now. My question is how long do you think it will take for a more simple, and more power conversion to come along.

Hi, Greg -
Why don't you do you own conversion? I'm never fond of waiting for somebody else to do something. That's just me; )

- Lynne

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