Canoe inspiring a racing SUP design?

Discussion in 'Boat Design' started by uvi, May 2, 2020.

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  1. uvi
    Joined: May 2020
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    Location: New York

    uvi New Member

    researching design for a really efficient flat water sup racing hull. Obviously it's going to be compromised due-to the 14' Length standard. First question comes to mind, what is the minimal Length to Beam ratio needed so wave drag isn't a major factor? Is it realistic given the limitations?
     
  2. Tiny Turnip
    Joined: Mar 2008
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    Location: Huddersfield, UK

    Tiny Turnip Senior Member

    IIRC, opinion is generally you should be aiming at 8:1 or skinnier.There will be other folk here who will be able to give you chapter and verse. That would be 21 inches for a 14 foot hull. Obviously stability is the big trade off. Here's an interesting point of reference for standing stability on a long slender hull - in this case much longer than 14 feet. Check out the white hulled solo boats. I talked with an old fellow who used to do this in his youth, and he swore some of the hulls were as narrow as 9 inches.

     
  3. uvi
    Joined: May 2020
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    Location: New York

    uvi New Member

    8:1 or 14'x21" is doable for the conditions above. The 25 mile around Manhattan is the race I have in mind for the board. Could be facing up to 2ft chop, strong currents and boat wakes so have to be more generous with width, say 23"
    I'm shooting for 5.5mph average. The best ratio I could eke out was 7.3:1. I wonder how much wave drag is going to be a factor with at that speed and ratio?
     

  4. uvi
    Joined: May 2020
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    Location: New York

    uvi New Member

    After studying some racing canoe shapes I have a basic draft for my board design and so I have some more hydrostatics. Maybe someone with understanding could jump-in regarding wave resistance (and resistance for that matter):
    Board dimensions: 14' x 23" x 9.8" @ 215L (Dugout board)
    LWL - 13'9.7"
    BWL - 22.6"
    Cp - 0.71
    Cb - 0.5
    Draft - 3.2"
    LCB - 7'.06"
    Length to Beam Ration - 7.3:1
    Wetted Surface - 19610.2 CM2
    Fully loaded: Rider+gear+board (estimated) Volume below waterline = 99.9L
    Estimated hull speed: 5.75MPH
     
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