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67197Re: [bolger] Re: Micro Construction

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  • John Kohnen
    Dec 26, 2011
      When you try to push a displacement boat faster than "hull speed" the
      amount of horsepower needed to go faster increases very quickly. Going
      from 2.5 hp. to 5 hp., say, might not make much difference in the top
      speed of a Micro. Using 20 hp. might make a Micro go noticeably faster,
      but I'll bet the wake was spectacular! Like watching the tugboat races. <g>

      The reason you want some extra power over what you need to reach hull
      speed in calm conditions is so you can overcome the windage when bucking a
      strong wind. Even motoring crooswind when it breezes up a feeble motor
      might not have the oomph for decent steering. A friend of mine has a
      Birdwatcher 2 that really speeds along with a 2 hp. motor in light winds,
      but he's discovered that if he tries to go against a 25 mph. (or somewhere
      around that, I don't recall exactly) with the mast up he barely he barely
      moves. Extra power will also help the boat keep moving against a chop.

      Another nice thing about having extra power is that in easy conditions the
      engine will be more pleasant to live with as it (relatively) quietly putts
      along at part throttle at cruising speed. :o)

      On Mon, 26 Dec 2011 07:52:22 -0800, Jeb wrote:

      > Just have a question regarding engine size to hull speed ratio. A 2.5
      > Yamaha 4 stroke will get my Micro up to hull speed (I believe
      > approximately 4.5 kts.) If I increase power the boat will not go faster.
      > Only the bow wave will increase. So my question is what advantage can be
      > gained by increasing power, especially against current or tide?
      > ...


      --
      John (jkohnen@...)
      Sin lies only in hurting others unnecessarily. All other "sins"
      are invented nonsense. (Robert A. Heinlein)
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