Design modification when the designer suggests it is possible?

Discussion in 'Boat Design' started by Murky Deep, Feb 11, 2021.

  1. Murky Deep
    Joined: Jun 2020
    Posts: 18
    Likes: 1, Points: 3
    Location: Massachusetts

    Murky Deep Junior Member

    I am putting together this boat from one of Gardner's books for fishing and general use (first image). In the current build, I am not changing anything from the design other than using marine plywood for the bottom instead of cross plank. Cross plank demands more skill at carpentry than I possess.

    Yesterday I reread the chapter searching for some piece of information and noticed the second photo, where Gardner states the boat redrawn with "considerably more" rocker would make a good sailboat for sheltered or semi-sheltered waters. In the future, this is a very tempting proposition, as I like tinkering with designs. The question is how much more? From the many hundreds of hours I have spent staring at boat plans, It seems that the stern transom would also need to be pinched in. The boat has 3" inches of aft rocker, in the sketches I have made, it looks like a sailboat with 6-7" of aft rocker.

    Any input or suggestions?

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  2. Olav
    Joined: Dec 2003
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    Location: Filia pulchra Lubecæ

    Olav naval architect

    Murky Deep,

    to be honest I would then consider a new design from scratch if you intend to build a sailboat.

    Sure, just about anything will sail in some way if you put a rig on it, but I doubt the boat from that book would be a good choice for sailing. The wide stern would cause terrible drag when immersed and with the almost wedge-like shape the bow would sink in significantly when the boat heels.

    A little sharpie hull like this is drawn very quickly and could then be designed for this particular purpose (i.e. sailing instead of motoring). Shoot me a message if I can be of any help; sounds like a nice fun winter weekend project to make some drawings and crunch some numbers. :)
    BlueBell and bajansailor like this.
  3. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    It says "boats of this type" meaning flat bottom boats with a square stern; not that boat in particular.

  4. Mr Efficiency
    Joined: Oct 2010
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    Location: Australia

    Mr Efficiency Senior Member

    Can you explain the physics of that for me ?
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