Atkin's Happy Clam's propeller

Discussion in 'Props' started by Dave G 9N, Sep 15, 2024.

  1. Dave G 9N
    Joined: Jan 2024
    Posts: 158
    Likes: 68, Points: 28
    Location: Lindstrom MN

    Dave G 9N Senior Member

    The point of asking about this boat was to decide whether it could reasonably be expected to perform as advertised. From the answers I have gotten, it just might. 2 blades looks like the most efficient option. The optimum 2 bladed prop diameter and rpm is easily calculated. Thank you Adler. To figure out the pitch, build the boat, install an engine and prop and test it. Not as clean cut as I might have liked. It might be interesting to find the answer.
    I indicated that the link to WBF was just to document the source of the quote. I'm pretty sure you realized that zero pitch was part of the rationale for discounting the test results and 35% slip was from a slip table, so you're having me on. No worries. You asked for data in post 39. Everything available is in post 40. You asked again in post 42, and it was in the attachment to post 43. Three data points. 2 calculations by the designer and one flawed test. 3 speeds, one real engine, two hypothetical, one rpm and an erroneous pitch. Insufficient data, understood.
     
  2. skaraborgcraft
    Joined: Dec 2020
    Posts: 710
    Likes: 226, Points: 43
    Location: sweden

    skaraborgcraft Senior Member

    At least "Happy Clam" was tested. The issue I had with some of Atkins claims was that in some designs, including a boat he had built for his own use "we.re here", did not match the claims he made it should achieve. I was always left wondering what formulas he used to calculate his predictions, and how much was guesswork based on past experience. I was also doubtful about his claims for "Surprise", but it was later established accurate by a user.
     
  3. gonzo
    Joined: Aug 2002
    Posts: 17,545
    Likes: 2,054, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    I really like Atkins designs. I also believe that he exagerated the performance to sell them.
     

  4. rangebowdrie
    Joined: Nov 2009
    Posts: 315
    Likes: 135, Points: 43, Legacy Rep: 10
    Location: Oregon

    rangebowdrie Senior Member

    Me too, studied the drawings of every design of his I could find in print, starting ~60 years ago.
    And yes, he probably did "bend the curve" a bit at times. I got a feeling that much of his data was more-or-less empirical.
    Dave, you've probably already done several times as many calculations for that boat as Bill ever did, lol.
     
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