Electric Waverunner?

Discussion in 'Boat Design' started by jaredhoefsmit, May 15, 2009.

  1. jaredhoefsmit
    Joined: May 2009
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    jaredhoefsmit New Member

    Hi All,

    To be honest, I'm a complete noob when it comes to watercraft (been a car guy my whole life), well anyways, I'm moving to a lake house that does not allow gas engines.

    So long story short, I was wondering if there are any electric waverunners that would fill the void?

    Sorry if this is in the wrong section, I honestly don't know where to start!

  2. mydauphin
    Joined: Apr 2007
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    Location: Florida

    mydauphin Senior Member

    It would be more like a wave crawler.... Not enough HP for speed. Get a Torpeado powered canoe. May be get 10knots out of it. May be someone else has more ideas.
  3. marshmat
    Joined: Apr 2005
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    Location: Ontario

    marshmat Senior Member

    Hi Jared,

    The power needed to get a PWC (jet-ski, sea-doo, waverunner, etc.) to get up and plane is really quite large. A few folks have reported swapping the gas engine out for a 5hp or so electric and a battery pack, but the result is pretty much stuck at displacement speeds- 5 knots or less on a hull like this. A PWC that can't go fast and can't jump isn't going to be much fun.

    Depending on what you want to do with the boat, you could go a couple of ways. If fishing is your game and speed doesn't matter, an aluminum utility or jon boat with an electric outboard (Torqueedo or similar) would probably do the trick. If you want to go a bit faster on electric only, you're looking at something long, light and skinny.

    You'll find a friend with almost the exact same situation on this thread: http://www.boatdesign.net/forums/boat-design/seeking-speed-3hp-electric-outboard-27388.html
  4. redoctober
    Joined: May 2010
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    redoctober New Member

    Electric PWC

    I made an electric PWC and it is a gas. I used 290 lbs of lithium cells in place of the gas engine, gas tank, and exhaust, etc. I used a hi revving hi torque, 3 phase motor, which is liquid cooled. It goes lightning.
  5. J3
    Joined: Jun 2010
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    J3 Junior Member

    What's your top speed?

    And how much run time do you get on average?

    Can you post some pictures of your setup.
  6. redoctober
    Joined: May 2010
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    Location: cabrillo beach CA usa

    redoctober New Member

    Hi J3
    I am new to this forum, and I replied, but it didnt take. My fault, I am sure.
    Run times vary on amp hours used. Low of 60 amp hours gets about an hour.

    filled with 160 amp hours, also at 96 volts, it should do alot better. Im working on that now. I am hoping to get a few hours. We'll see.

    Top speed is about 65, Im guessing. I have no knot meter hooked up. Charge time is about 1.5 hour right now. I have not done an on board charger yet. Soon!

    Either way, this has been alot of fun, its totally quiet, and so far...reliable. Ill try to get a pic attached somehow. I am not familiar with doing that, but will learn.
  7. Squidly-Diddly
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    Squidly-Diddly Senior Member

  8. Jerseygirl
    Joined: Jan 2015
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    Jerseygirl New Member

    Dear Redoctober:

    Using a three phase motor, doesn't that imply an AC power source? Did you need three inverters so you could convert battery to AC?

    Have you had any success with future improvements since the above thread?
  9. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Just do the math. Lets say you have a 40 HP jet, so you'll need a 30KW motor for the same performance envelop. Now figure out how much battery you'll need to sustain a full load, on a 30KW motor for an hour and the you'll quickly see why there's no electric wave runners blasting around. The best part is getting pricing on a 30KW motor, which will be your second eye opener.
  10. messabout
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    messabout Senior Member

    Jerseygirl, there are speed controllers with the ability to convert straight DC to three phase, no problem (except cost). These are the standard controllers for modern model cars, boats and planes. These model motors, called brushless by the modelers, are three phase types, they deliver more power than the old style brushed motors of a similar size. Not to say that they deliver appreciably more power for the same input wattage. Some claim that they do. They are more efficient so there may be a net input/output gain.

    With all that, I am skeptical about the practicality of an electric waverunner (jetski) in the standard configuration.

    I suspect that the forum members might have fun arguing about the most favorable design for an electric boat that had moderate speed potential,.......... say 22 knots. That's fast enough to jar your teeth in a chop.

    For sure it would not be a water pumper. It would almost surely have a prop.

    I'll start by suggesting a L/B ratio of four or more, almost flat bottomed, about 8 Kw, 3 phase, Lipo batteries, cost a plenty, lots of voltage, 25 cells more or less. Solo because of weight restraints versus power output.

    I reckon there are some of the forum guys, or girls, who could contribute some sage advice about such an imaginative project. I'm thinking that Jeremy Harriss could weigh in on this with some good advice. Not to diminish the many other clever and educated members who could do the same. :D
  11. Dave T
    Joined: Sep 2011
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    Location: Anamosa Iowa and North Buena Vista on the Mississi

    Dave T Senior Member

    Before investing in an electric fairly high speed wave runner I'd check with your neighbors and the local DNR. Usually the reason lakes are restricted to electric is not just to reduce noise but also to restrict speed for the safety of swimmers and not to disturb people fishing etc. How big is the lake? What are the wake restrictions?
  12. DennisRB
    Joined: Sep 2004
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    DennisRB Senior Member

    You say its for use at your "lake house", so I assume flat water use among slow craft (as none use gas). The typical jetski type platform evolved to the shapes and heavy weights that they are thanks to the fact they are used with HUGE hp engines for the length of the boat. So fitting an electric engine will not be the best idea in that hull.

    Now if you changed the whole hull concept and built it around electric propulsion with considerably less power and speed, you could probably come up with something that has decent speeds and is efficient enough for your usage.

    The hull/s would probably be longer and much lighter. I think a small power cat or tri with one or 2 seats could be made to work with decent speeds and run time.
  13. bpw
    Joined: May 2012
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    bpw Senior Member

    Yep, I suspect an electric jet ski even if legal currently, would last about one season before the rules got changed.

    Not to mention the very high likelyhood of pissing off all your new neighbors.
  14. DennisRB
    Joined: Sep 2004
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    Location: Brisbane

    DennisRB Senior Member

    Another reason to use some sort of small electric power cat. At least it wont make a big wash.

  15. intrepid71
    Joined: Jan 2005
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    intrepid71 Junior Member

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