scale model- forefoot too deep?

Discussion in 'Boat Design' started by BE_, Mar 7, 2023.

  1. BE_
    Joined: Jul 2021
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    Location: Virginia

    BE_ mr. man

    making a 1/16 scale model of a theoretical 12 foot v bottom skiff. i have been told that a deep forefoot will catch waves and turn the boat, would that be a problem with this design?

    i made it this way because it is simpler, but i would change it if necessary.

    IMG_20230307_190916345~2.jpg
    IMG_20230307_191009963~2.jpg
     
  2. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    Yorkshire cobles are generally well regarded for their seaworthiness, and they usually have a much more pronounced forefoot than your skiff.
    Here is some background info about them -
    The Yorkshire Coble | Lodestar Books https://lodestarbooks.com/the-yorkshire-coble/

    There is a lot of 'twist' in the bottom of your model in way of the bow - when you build the full size version will you 'plank' this section in narrow strips?
     
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  3. messabout
    Joined: Jan 2006
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    Location: Lakeland Fl USA

    messabout Senior Member

    A deep forefoot on a sixteenth scale model of a 12 footer will tell you nothing of value. A 9 inch model ? You won't get much information from a nine inch model that is being tested in water. A twelve footer needs at least to be a quarter scale model if you are to get any usable observations from splashing the model.

    Lo0ok at it this way............a 16th scale model of the twelve footer must be as light as a feather in order to have any similarity to the full sizes boat. Lets say that the twelve footer is to weigh 150 pounds and the occupant and gear would weigh 200 pounds. All up weight 350 pounds. That means that your sixteenth scale model will have to weigh less than 2 ounces if presumed to have scale weight. Build to quarter scale and the model can weigh 350/64 = 5.4 pounds. That is more realistic and the model will behave far differently from the tiny sixteenth scale model.

    You have drawn what appears to be a planing boat. When planing, the forefoot will probably be above the water and the deep forefoot will be of only small concern. When going slower, not planing, the boat will be unpleasantly twitchy in quartering seas. At slow speed , in dead calm water it will not matter except that steering response might be a tad slower.
     
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  4. BlueBell
    Joined: May 2017
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    Location: Victoria BC Canada

    BlueBell . . . _ _ _ . . . _ _ _

    Good points messa and bajan.
    I think this one's for his key chain, no?
     
  5. BlueBell
    Joined: May 2017
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    Location: Victoria BC Canada

    BlueBell . . . _ _ _ . . . _ _ _

    BE_

    I just read through your previous thread from last year,
    and want to be sure you are aware that matching a SOR (yours of course)
    to a reputable and proven design,
    would be waaaaaaaaay easier and a lot faster, cheaper, and
    much, much more likely to succeed.
    I know it's fun but it's just so very likely to fail, many, many times over before you get it right.
    And you never really know when you're going to be out on the water,
    2 years, 4 years, 8 years... never...
    Consider it.

    Then go look for that design already built, by someone like you, for sale!
    Someone who was diligent and mindful throughout the build.
    It will cost a fraction of what they put into it and it's already built, tweaked and running!
    You could be boating the next day.
    Your call.
     
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  6. BE_
    Joined: Jul 2021
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    Location: Virginia

    BE_ mr. man

    yes
     
  7. BE_
    Joined: Jul 2021
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    Location: Virginia

    BE_ mr. man

    the model is to test building techniques- make sure the parts go together right. not as much for testing performance.
     
  8. Ad Hoc
    Joined: Oct 2008
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    Location: Japan

    Ad Hoc Naval Architect

    You have some great advice/guidance from BajanS.

    However, in addition...if the forefoot is not significantly below the stern, when floating at level trim, you're going to be ok.
    It is only when there is a significant depth difference to the forefoot, relative to the stern bottom of the transom does it become and issue.
    That's when it acts like a large fwd rudder....:eek:
     
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  9. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    Your model seems to be based on a Chesapeake deadrise boat; at least from the profile. Those boats are long and narrow. The beam ratio on your model is a lot larger.
     

  10. BE_
    Joined: Jul 2021
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    Location: Virginia

    BE_ mr. man

    it is based on the deadrise. older displacement hull deadrises were narrow, but the length to beam ratio on modern deadrises is 3:1 (atleast as measured on Google Earth), same as my model.
     
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