ultimate 3.5 M tri

Discussion in 'Multihulls' started by rapscallion, Sep 22, 2007.

  1. rapscallion
    Joined: Oct 2006
    Posts: 504
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    Location: Wisconsin

    rapscallion Senior Member

    I'm ready to build the first 3.5M tri. Could someone send me their ideas in an email so I can actually start building one?
     
  2. Doug Lord

    Doug Lord Guest

    Google "International 3 meter trimaran" and you'll come up with the class as it is today in the Pacific northwest. I believe the Northwest Multihull Association has free plans from John Marples(ST. Augustine Fl.) But you might have more fun with Chris Ostlind or Kurt Hughes 12 footers. 3 meters is just too small, in my humble opinon. The cost difference will not be too significant but the performance difference surely will.I think building a class with 12 footers may
    be easier than with the 3 meters.
    I might even be interested in doing a 12 footer if the rules can be agreed upon stipulating a MINIMUM crew weight of 220 pounds(for racing only).....
    NWMA - 3 Meter
    Address:http://nwmultihull.org/3meter/3mtr.htm Changed:9:35 PM on Wednesday, January 10, 2007
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    12' trimaran
    Address:http://www.multihulldesigns.com/stock/12tri.html Changed:4:49 PM on Sunday, November 26, 2006
     
  3. rapscallion
    Joined: Oct 2006
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    Location: Wisconsin

    rapscallion Senior Member

    220 lbs? I don't have a problem with that.... but what do us skinny guys do... Add weight to the boat?
     
  4. rapscallion
    Joined: Oct 2006
    Posts: 504
    Likes: 15, Points: 18, Legacy Rep: 132
    Location: Wisconsin

    rapscallion Senior Member

    stressed ply would probably be the lightest way to go, but I'm thinking of using PI foam (cheap) with cheap stringers... and set up the mast without spreaders.

    I have a Kurt hughes design book. I'll do the best I can from that I guess.

    If it doesn't fall apart right away maybe I'll slap some foils on it.
     
  5. Doug Lord

    Doug Lord Guest

    Lightweights

    -------
    Since small unballasted performance boats are so sensitive to weight it makes sense to me to have a weight equalization plan that ensures everyone is on the same level. And since you would sit in the middle like a 2.4meter(or Kurt Hughes 12 and Chris Ostlinds 12) the equalization weight could easily be added in one place since it doesn't have to be movable.
    So designs for this "class" would require that the crew sat in one place and that the minimum "crew" weight was 220. A minimum all up boat weight might be required to prevent a carbon war.
    Maximum SA?(suggestion: 100 +120 spin?)
    -----------
    OR:
    Let the heavyweights carry more SA upwind and down so that the lb.of sailing(boat + crew) weight per sq.ft. of SA is the same .
    Example:
    -------
    Lightweight- 160lb. boat +160lb crew=320lb.. SA= 100 sq.ft. or 3.2 lb/sq.ft. SA
    -----
    Heavyweight- 160lb. boat weight + 220lb.=380lb.
    SA at 3.2 lb. per sq.ft.= 118.75 An additional "weight factor" might be required that would increase the "heavyweight" SA a bit to account for having a heavier boat on the same waterline length.
    ------------
    Just a few ideas-the concept of a small, fast tri with a wide crew weight range interests me. A boat like this could easily become a lightweights only class unless the founders of the "class" plan for a wide range of crew weights.
     
  6. rapscallion
    Joined: Oct 2006
    Posts: 504
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    Location: Wisconsin

    rapscallion Senior Member

    good thoughts Doug...

    I like the idea of adding ballast to make up for crew weight the most, simply because it seems to be the easiest way to manage the differences at a regatta.

    I also like a minimum weight to prevent a carbon war. My thoughts on such a class would be a VERY high performance development class that was dirt cheap to participate in and could easially accomidate disabled sailors...

    we could do a 3.5M box rule with a minimum weight and maximum SA (still not sure what that would be)

    But the one thing I wanted to throw in the ring is that the boat CAN'T turn turtle. I was going to form a foam/epoxy wing to go on the top of the mast that would act as an endplate for the foil and provide enough ballast to prevent the boat from turning turtle.

    It should actually make the sail more efficient and add safety for those sailors who would have a hard time getting out of the boat if she went over.

    Anyone know where I can find info on calculating scantling numbers for multihulls?
     

  7. jamez
    Joined: Feb 2007
    Posts: 490
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    Location: Auckland, New Zealand

    jamez Senior Member

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