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2354RE: [AtkinBoats] Re: Plans

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  • Alan Boman
    Jul 3, 2009
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      One of the available outputs of the freeware hull modelling software
      "FreeShip" (now called DelftShip) is a graph of speed versus drag for a
      given hull. (Drag can be converted to Kw or HP).

      There is no way of knowing how accurate the algorithms in the program are in
      absolute terms, but if you simply wanted to compare two relatively similar
      hull designs, it probably wouldn't matter much.

      The hull resistance graph for Atkin's "River Belle" hull is attached for


      From: AtkinBoats@yahoogroups.com [mailto:AtkinBoats@yahoogroups.com] On
      Behalf Of calfee20
      Sent: Saturday, 4 July 2009 3:06 AM
      To: AtkinBoats@yahoogroups.com
      Subject: [AtkinBoats] Re: Plans

      --- In AtkinBoats@yahoogroups.com <mailto:AtkinBoats%40yahoogroups.com> ,
      "Alan Boman" <alan@...> wrote:
      > HI Tom,
      > Rescue Minor and Shoals Runner are very similar as you suggest. Mr William
      > used the same hull shape, in a number of different lengths, over many
      > years. I am building a River Belle, which is the same shape again, but 36'
      > long. I had no trouble lofting the Offsets Table into a set of workable
      > plans, and the Plan/Profile drawings I received from Pat Atkin supplied
      > remainder of the details.
      > I notice that the Shoals Runner has a slightly more complex shape in the
      > after part of the chine, but otherwise seems very much the same as Rescue
      > Minor. Given that Mr William continuously refined his Tunnel Stern designs
      > over the years, the only significant difference may be that Shoals Runner
      > from 1958 and Rescue Minor from 1944 and were any improvements made, then
      > the later design would be the better choice.
      > Just a thought.
      > Alan

      Too bad you couldn't put models in a tank to measure efficiency. It seems
      these "active" hulls need to be driven.

      I forget his name Mr Gnome? from Bagley boatworks wanted to do a test on
      these hulls but I recently went to his site and found they had fallen prey
      to our world wide recession. I'm afraid to say the D word.

      Anyway the only way I can think of to make tests would be to make ACCURATE
      RC models and switch the same power drive from model to model and measure
      speed and current draw.

      Just a thought.....................Tom C

      [Non-text portions of this message have been removed]
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