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  1. #11
    Join Date
    May 2007
    Posts
    29,393

    Default Re: Bison 55 electric outboard review

    Quote Originally Posted by Tranona View Post
    The problem is that even if the motor is producing that power it is not converted into thrust because of the small high speed prop. Good for mixing your cocktails quickly but not for pushing a heavy flat bottomed dinghy. On the other hand an Seagull with low power output but a big slow turning prop will do the job.
    Some truth in that, but I think it the OP's view, it does the job?
    No propellor is every 100% efficient, how small are the Bison props? Much smaller than a Yamaha 2hp prop?
    One horse will move a canal barge much faster than either a Yam 2 or Seagull I think.
    An actual bison might be better still, but only if there's a towpath.

  2. #12
    Join Date
    Nov 2007
    Posts
    39

    Default Re: Bison 55 electric outboard review

    Does anyone know the amperage rating of these outboard motor control switches, apparently they are used by lots of manufacturers. Additionally they have 6.3mm? (old one in the shed, will measure later) blade connectors, does anyone know the amperage rating for a 6.3mm blade.

    Minesapint

  3. #13
    Join Date
    Nov 2007
    Posts
    39

    Default Re: Bison 55 electric outboard review

    Quote Originally Posted by Murv View Post
    There are conversions you can do online, but they're pretty feeble compared to a petrol.
    My 63/65lb thrust pushes a 10' tender against the tide at a reasonable pace, maybe 3 knots or so, so possibly 1hp, something along those lines?
    Just found a statement on line

    1hp is equivalent to 550lbs of work per second. Although they say there is no direct comparison.

    So I guess my 55lb outboard is one tenth of a horsepower?

    No doubt it is feeble compared with a 2hp outboard and is much heavier when the weight of the battery is taken into account but given 2 identical dinghys I would not be able to keep pace with the electric powered outboard with a set of oars.

    Minesapint

  4. #14
    Join Date
    Nov 2012
    Location
    Kent
    Posts
    1,789

    Default Re: Bison 55 electric outboard review

    Quote Originally Posted by MINESAPINT2 View Post
    Just found a statement on line

    1hp is equivalent to 550lbs of work per second. Although they say there is no direct comparison.

    So I guess my 55lb outboard is one tenth of a horsepower?

    No doubt it is feeble compared with a 2hp outboard and is much heavier when the weight of the battery is taken into account but given 2 identical dinghys I would not be able to keep pace with the electric powered outboard with a set of oars.

    Minesapint
    That's interesting, guess I was way off then! I suppose it's the issue of once you've reached hull speed of a displacement dinghy, then more power isn't much help.
    My little 2.5 is certainly a bit faster, but it's just so much easier with the electric one.
    I always used to row to my mooring, but after a particularly eventful journey against a strong wind and tide (45 minutes of rowing for a 1/4 mile journey) I switched to a motor!
    I was working on the boat on Monday, coming back against the near gale and a strong tide was absolutely no issue at all for the bison. I wouldn't have even tried it if I only had the oars.

  5. #15
    Join Date
    Jun 2001
    Location
    Oban
    Posts
    631

    Default Re: Bison 55 electric outboard review

    Quote Originally Posted by MINESAPINT2 View Post
    Just found a statement on line

    1hp is equivalent to 550lbs of work per second. Although they say there is no direct comparison.
    I should lose that online source.

    Horsepower is a measure of power in the same way that Watt is. One HP = 746 Watt.

    The original definition of HP is 550 foot.pounds/second so a force of 550 pounds moving at 1 ft/sec is exerting 1 HP. If it goes faster, the force of 1HP goes down e.g. 55 pounds at 10 ft/sec is also 1 HP.
    More simply, a force of 1 Newton moving at 1 m/sec is exerting 1 Watt.

    Electrically, 1 Volt at 1 Amp is 1 Watt but putting an electric Watt into an outboard will be sure to get less than 1 mechanical Watt out to the dinghy.

    Derek

  6. #16
    Join Date
    Aug 2013
    Location
    SW Scotland
    Posts
    16,178

    Default Re: Bison 55 electric outboard review

    Quote Originally Posted by cpedw View Post
    The original definition of HP is 550 foot.pounds/second ...
    Watt himself did measurements on the work output of horses, and concluded that the average horse could keep up 22,000 ft-lb per minute. He then bumped that up to 33,000 ft-lb per minute (your 550 ft-lb per second) so that purchasers of an "8hp" (say) Boulton & Watt engine would be pleasantly surprised at how much better it was than eight horses.
    "Seamen are always wanting to do things the proper way; and I like to do them my way."

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