Cannibalize a Toyota Prius for a boat powerplant?

Powerboats are noisy.  Electric boats have limited speed and range.  Why not a hybrid boat?  The Toyota Prius can pull itself along at low speeds with only its electric motor.  Why not find a wrecked Prius and remove its vital organs to form the basis of a fantastic power boat:  silent when poking along the shore but capable of cruising at 20-30 knots at the cost of a big increase in noise.


25 thoughts on “Cannibalize a Toyota Prius for a boat powerplant?

  1. I’ve often thought a quiet two-stroke engine would make one a lot of money.

    Snowmobiles, jet skis, motorcycles, yard blowers, lawnmowers, etc. all make a huge racket due to their cheap and effective but noisy little internal combustion engines. Perhaps “someday” electric engines will match them in power per weight (which really seems to matter) and power per dollar (which matters less, but also).


  2. Prius’s tiny engine will not be able to propel anything larger than a dinghy at reasonable speed. USians like their boats fast, and most inboards are powered by a marine version of Chevy V8 giving 250HP or more. To get a mass-produced 26ft boat with all the amenities to the planing speed one needs at the very least 170HP.

    There are lots of European steel boats that cruise at about 10 knots, are much more seaworthy, have more interior and deck space, depreciate less if at all and are diesel powered and reasonably quiet due to a separate silencer (as opposed to straight through-the-transom exaust). Noone buys them in US. They are not fast and flashy enough.

  3. Two thoughts-

    Can a boat generate the energy from “braking” that an auto hybrid does to power up the battery half of the power plant? Do boats brake at all, or just throttle down?

    Also, there are new computer-assisted fuel injected two stroke engines in production motorscooters (Aprilia Di-Tech scooters, Orbital Engine Co. – Aus.) They generate more power and run a lot cleaner than traditional two strokes as the fuel injection system burns afar greater percentage of fuel. Not sure if there have been marine applications.

    I’m always frustrated when environmentally-friendly efficiency is seen as the enemy by traditional industry. Efficiency means more power generated per fuel unit as less fuel is wasted. I think it is the short-sighted quarterly profit focus that makes companies resist a little investment in efficient technologies that could increase productivity and profit in the longer run.

    -John Irvine

  4. Ryobi developed a compact 4 stroke engine a couple of years ago which runs cleaner and more powerful than any two stroke even with electronic injection. I have one on my weed wacker. It’s loud as hell though. Well this wasn’t entirely on topic…

  5. I’m not sure how recent this is, but Honda has also developed some form of a compact 4-stroke that has been applied to some models in their personal watercraft line. I can’t speak to the noise factor, but a good reason is lower emissions and longer engine life.

    As for hybrid boats, as with the comment above, I’m not sure how the generation part would work. The closest parallel to regenerative braking, that I can come up with now, would be to use retractable fins to redirect flow from the underside into channels where they could spin a turbine (think hydroelectric dam), but I’m not sure how efficient that would be. Alternatively, you could always slap PV cells on the top and hope it doesn’t get to overcast.

  6. Honda, Suzuki and others have been selling 4 stroke outboards for years. They are touted as being very quiet. At 30 knots, you might end up with more wind noise than motor noise.

    If you do put a Prius motor in a boat, you might want to check into “marinizing” it. There are kits that do this for American auto engines (older ones anyway). It shifts some of the parts that rust into non-corrosive material. I believe it also does some minor mods to make it safer (no sparks to ignite fuel vapors in the bilge?)

  7. Hey, why not a hybrid boat? Well, they do exist — some large yachts and/or small ships have diesel electric drivetrains, like locomotives. Also, electric trolling motors are popular with bass fishermen. And then there are things like bow thrusters, electric windlasses, etc. So many boats are halfway there already.

    Modern generator sets are really quiet, and electric motors are very small, simple, and reliable, and don’t require a separate gearbox — just a switch to go backwards. I think the way to go about this is to forget the Prius (which has a much different set of service requirements), and use a standard marine generator set, a big bank of deep cycle batteries, an off the shelf maring charging system, and an electric motor of your choice.

    For a start, look at the Conser-designed catamaran featured in one of the sailing (Sail? Cruising World?) magazines recently. It has just that — a regular genset powering two electric motors, one in each hull. I suspect this was to avoid the extra weight, expense, fuel consumption, and maintenance hassles of two complete, diesel drivetrains. Also, look at Duffy electric boats from Newport Beach, CA. Just do it like they do, but add the genset.

    I’ve thought about this stuff a lot. Boats are getting to where they have a lot of electric accessories — bow thrusters, anchor windlasses, electric winches, and all the appliances and comforts of home. For a sailboat especially, it makes sense to just have a central electric power source, and run everything off that, including the propulsion motor. For a powerboat, it makes sense to have an auxiliary electric “marina” motor, so you can let your neighbors sleep (and breathe).

  8. Just use an inboard engine. Outboards are essentially small motorcycle and car engines (ie: the biggest Honda outboard is/was based on the Accord’s 4 cyl. engine) in a thin casing with pathetic technology (carburators are common and four stroke and injection are being touted as huge advances…)

    Gasoline inboard are almost all GM I4, V6 or V8 power plants, the newer one have electronic injection.

    Diesel inboards have gone bounds and leap ahead though. Check out Yanmar. Typically, replacing the 454’s in a large-ish (~40 foot boat) with a pair of Yanmar’s will improve fuel economy, range, top speed and lower noise. Of course it’s japanese.

  9. Wouldn’t work that well for a speedboat, but if you intent was the auxilliary engine for a sailing yacht, then you have an excellent point…

  10. A through the wave trimaron displacement hull boat that was electric at low displacement speeds and 4 stroke at higher speeds could be acheived using a square stern canoe type boat mated to a small catamaran powered by a 4 stroke outboard with high thrust electric motors bolted to the cavitation plate. I do wonder if both type motors could be used at the same time to increase horsepower similar to hybrid cars. Regenerative braking would be scrapped but solar panels on the bow and canopy supplemented by small wind generators on the outriggers would be welcome as a weekender camper for inland lakes or perhaps even for coastal cruises. Of coarse the devil is in the details but dreaming is fun.

  11. Energy recapture(during the braking process) is mainly what recharges an automotive hybrid vehicles’ battery cells. Boats do not employ the same friction process to stop, so todays auto hybrid technology cannot be shared or copied in the marine world.
    However, what about steam? Todays submarines use nuclear power to super-heat water into high pressure vapor(steam) which then powers huge turbines.
    For recreational and commercial power boats, think hydrogen as the fuel and steam as the force. The end result is a very powerful system that produces only h2o as an emission. As far as safety goes: boats, typically, are not involved in the horrific high speed crashes that autos are subjected to, therefore reducing the amount of hydrogen related explosions.

  12. Re: philg question on prius in a boat and regeneration. Don’t give up on regeneration in a boat, although it doesn’t come from braking but from anchoring in a current. Wondering if you went anywhere with the boat Prius drive ( Toyota calls it Synergy ). That is exactly where I want to go with my boat but don’t have all of the skills to pull it off and have had a hard time finding a wrecked Highlander or other larger Synergy. Also, my boat carries passengers for hire so reliability is the priority.

  13. I am convering aqn old aluminum starcraft boat to a hybrid. It is an inboard/outboard and I am using parts from a wrecked Prius. If it works I will build boats for other people that want to use less gas. I will Know soon.

  14. Briggs and Stratton now makes small electric outboards, Honda makes small generators. Add batteries and you have a hybrid boat (and possibly solar powered if you add solar panels to do some of your recharging). Most of us like to go boating on the long sunny days of summer and out in the lake you should have lots of solar exposure. The problem is getting enough power to get up on plane with a boat that is big enough to carry the batteries, so the issues are about performance rather than feasibility.

  15. If anyone has successfully retrofitted an existing boat with a hybrid drive, I would love to hear from them ( I am restoring an old boat and want to replace the existing V8 with a hybrid.

    One thing that I was hoping to find out is whether a hybrid system could realistically work if a 37KW motor was used. I see that the Frauscher electroyachts use it and they seem to move at a pretty good clip. Can a diesel generator/deep cycle battery combo work for a motor that size on a boat under 30′?

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