35ft offshore tri lines

Discussion in 'Multihulls' started by porkhunt, Jul 13, 2013.

  1. porkhunt
    Joined: Jul 2013
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    Location: auckland

    porkhunt New Member

    hi all, im an 18 year old currently unemployed boatbuilder, i've been lurking for a while but i thought i'd sign up and share my ideas. this is a 35ft foil assisted offshore racing tri ive been working on for the past day or two (instead of finishing my paddleboard which should have been done two months ago :rolleyes: ) 35ft main hull, amas 40ft oa, 37ft beam. it was just done with a pen and a shitty steel ruler as a batten, so it hasnt come out 100% (cellphone camera doesnt do this justice either) but you can see whats going on.

    while on the topic of tris- here is a (roughly) 1:12 model that i have designed and part built based on a 35ft tri i sail on, its all foam and carbon but only hot glued together for the picture which is why the amas are far too bow down. all up weight so far is 750g
     

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  2. Doug Lord
    Joined: May 2009
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    Location: Cocoa, Florida

    Doug Lord Flight Ready

    Welcome to the forum! Nice drawing, but do you have any numbers? Ama buoyancy as a % of total displacement, SA, SA/WS, L/B(length divided by beam at the waterline) of main and ama-would help to flesh out the drawing. Is it designed to fly the main hull? Do you know the anticipated boat angle of heel with the main hull just flying?
    Are you going to make the model radio controlled? Looks good except,as you point out, the bow down attitude of the amas.
     
  3. Gary Baigent
    Joined: Jul 2005
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    Location: auckland nz

    Gary Baigent Senior Member

    Really like your art work, Porkhunter.
    But you will upset a few here - how dare you not design by numbers first, none of this arty farty, creative stuff.
    Don't listen to them.
    A suggestion at this early stage; seeing as your main hull bow sections have low free board and low buoyancy, semi-Oracle-like, and your amas are beyond full length, you could reduce the main hull even more, not as far as a Decision 35 but say, halfway to that design. Then you have the advantage of a central hull platform and accommodation and strength plus the cat-like long floats and foils for stability.
    Anyway, don't listen to me either.
    Sounds like you crew on the Timberwolf?
     
  4. porkhunt
    Joined: Jul 2013
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    Location: auckland

    porkhunt New Member

    cheers doug, nope i have no such thing. about the most calculation that went into this drawing was 'yeah i think ill draw it about 400 long'. with my current knowledge of boat design- around zero- i'd say the ama is around 140% displacement. i havent drawn the port side of the ama so it looks a little narrow but 12 degrees of heel should see the main hull skimming the surface. i am trying to get onto the west lawn design course so i can start to understand all of the proper calculations. yes the model will be rc, hopefully foiling as well. just remembered, raising the main aka by 10mm sorted out the bow down attitude of the amas and made the sheerlines reasonably parallel.
     

  5. Doug Lord
    Joined: May 2009
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    Location: Cocoa, Florida

    Doug Lord Flight Ready

    ==============
    Sounds great-take a look at the MPX thread- a couple of pages back there is a link to a german RC multihulls forum- some neat stuff there.
    12 degrees seems just about perfect-USA 17 was 13 degrees and some tris are as high as 26 degrees! Good luck!
    PS- you should go visit Gary-he has designed some extraordinary trimarans..........
     
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