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1968Re: [AtkinBoats] Testing Billy Atkin's performance as stated by Atkin & Co

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  • Kenneth Grome
    May 30, 2008
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      Hi Lon,

      I am very familiar with the Atkin Seabright skiffs on the
      website, but thanks for posting the links since it makes
      them easy for others to find them.

      I guess you are "assuming" that the tunnel-stern boats are
      less efficient than the others based only on the figures
      posted on the website, is this correct? Or do you have
      factual evidence to support your conclusions?

      In my opinion those figures you pulled off the Atkin website
      are theoretical, not factual, and none of the folks who are
      seeking the answers to my tests will accept those numbers
      either. Besides, I'm talking about two hulls optimized for
      15 knots, and there is no way to know if Atkin optimized
      the hulls you mentioned for any particular speed -- or if
      they were optimized for anything else for that matter.

      In my opinion as well as the opinions of others, it is
      possible that the tunnel-stern version traps some of the
      moving, energy-filled boundary layer water under the hull,
      then it re-uses this trapped energy by funneling it toward
      the propeller where it is further accelerated. The
      non-tunnel-stern versions simply let this energy-filled
      boundary layer water drift away, and the energy it already
      contains is basically wasted.

      Although this is just a theory,it clearly supports the
      possibility that the tunnel-stern boats may be more
      efficient than the others. This is why, until I see some
      actual evidence one way or the other, I simply cannot
      accept yours or John Kohnen's assumptions.

      Regardless of which Seabright hull versions are more or less
      efficient than the others, no tests have been done to
      compare Seabright hulls with non-Seabright hulls as far as
      I know. So perhaps I still have a valid reason to run my
      own tests and learn the facts about the relative
      efficiencies of these two hulls?


      Ken Grome
      Bagacay Boatworks

      > The Atkin Seabright Skiff Tunnel hulls were designed
      > for inboard use in shallow waters, Atkin also designed
      > Seabright Skiffs that were not tunnel hull that did
      > not sacrifice performance for shallow draft, below are
      > two seabright skiffs about the same width and beam one
      > tunnel hull (shallow draft and the other slightly
      > deeper draft (5-1/2") but it requires less than half
      > the horse power to achieve greater speed.
      > Heron Seabright Tunnel hull
      > LOA 17 WL 16'-7" beam 5'-5" draft 6" 25hp 17MPH
      > http://tinyurl.com/5rzo2o
      > http://www.boat-links.com/Atkinco/Utilities/Heron.html
      > Happy Clam Seabright Hull
      > LOA 17 WL 16 beam 5'6" draft 11-1/2 10HP speed 20mph
      > http://tinyurl.com/345atw
      > So there it is
      > Lon
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