Hobie/J24 Trimaran Conversion

Discussion in 'Multihulls' started by Delane, Apr 17, 2005.

  1. bill broome
    Joined: Jul 2008
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    Location: sydney

    bill broome Senior Member

    why? got an excess j24? sell it, buy/build a tri. this kind of plan converts money and effort into a garden ornament.
     
  2. surf boat man
    Joined: Oct 2007
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    Location: australia

    surf boat man Junior Member

    pictures of my surf boat when I bought it

    these are the pictures of the surf boat when I bought it
     

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  3. Delane
    Joined: Apr 2005
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    Location: Okinawa, Japan

    Delane Senior Member

    Nearing Completion

    “Vitamin Sea” is near completion and should launch around the first week in June. Ordered and received a foil section, NACA 66-0012; 50cm root X 25cm tip X 71cm length) dagger board. Also utilizing H-20 daggers for the Amas and have a question regarding placement of the foil section relative to the original position of the as built J-24. Decided to use a standard J-24 Main, 110% Roller Furler and utilize water stays in addition to the existing new rigging.

    Once the position of the foil section is decided, I plan to butt weld a 25mm steel rod to the flat 4mm steel plate. Next fiberglass the foil section and glue to the rod (gussets included) and then epoxy and glass up all to the bottom of the keel stub. The thought is to make it relatively strong and yet not make holes in the stub as with the original lead keel. The attached pics illustrate the foil section and plate minus the 25mm rod. The rod will protrude into the foil section 15 inches. Question is where I should place the section relative to previous. I’m thinking as far forward as possible but it looks right positioned a little further aft.
     

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  4. BWD
    Joined: Aug 2006
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    Location: Virginia, US

    BWD Senior Member

    The foam in the picture looks light and non-structural (but very nicely shaped).
    But even if it's strong foam, it's only foam, and putting metal rod in it seems a waste. The problem is there is nothing strong connecting the 2 skins.
    Unless that foam is really really strong!

    Under sailing or grounding load the fin could flex and the rod could tear the foam apart, unless the glass skins are very thick and strong, in which case the rod is not needed at all.
    What I might put in there is a solid wood spar replacing all the foam at max chord, helping with grounding loads as well as serving as a sheer web.

    But if you ground hard, I think you could really trash this kind of fin anyway, unless the skin thickness was truly enormous. Even without the lead, it's no dinghy.
    The normal "light" alternative to a lead fin is a hollow steel one.
    I would have considered using a daggerboard that could crush or kick up. Feel like building a trunk?
     
  5. Delane
    Joined: Apr 2005
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    Location: Okinawa, Japan

    Delane Senior Member

    It's Alive (Vitamin Sea launched Labor Day Weekend)

    Yes it's true!

    Had two good runs in a bit of a breeze and a great celebration barbeque with family and freinds at the Marina.

    Speed to wind about 8 knots on the first run with the throttle at about 70%, sorry in the habit of translating for my power boater buddies who demand I break it down in those terms. Off wind seemed to be about the same but didn't have a JPS to verify the first day.

    Well, I'll let the pictures speak a little.

    Enjoy!
     

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  6. Delane
    Joined: Apr 2005
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    Location: Okinawa, Japan

    Delane Senior Member

    More Photos

    Here are some other shots of the first day!
     

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  7. Zilver
    Joined: Nov 2007
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    Location: Amterdam the Netherlands

    Zilver Junior Member

    Congratulations on the completion of your project ! Nice idea and boat.

    It looks like you were having a lot of fun on the maiden trip.
    Please report some more observations about how she sails when you can.

    Cheers, Hans
     
  8. mihari
    Joined: Sep 2009
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    Location: Greece

    mihari Junior Member

    Congratulations!!!!!
    Now we want to hear about how Sea Vitamin sails...
    She looks like a fun boat...
     
  9. sharpii2
    Joined: May 2004
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    Location: Michigan, USA

    sharpii2 Senior Member

    Congrats.

    I bet it even planes quicker than it did with a keel.

    It might be interesting sport to race it against keel versions to see how the performance compares.
     
  10. aussiebushman
    Joined: Oct 2009
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    Location: Taralga NSW

    aussiebushman Innovator

    Hi All

    I'm new to this forum but not to boatbuilding or to the idea of building a tri from donor parts. Unfortunately, I have to sell the Simpson catamaran I built(see www.mainproject.info for details) and now want to build a trailerable trimaran. The idea of using a surfboat is really interesting and stops me having to find a suitable trailer sailer to convert. The advice about using Hobie 18 amas instead of the 16's I was considering is very sound.

    I'm located near Sydney so if anyone knows where to locate a suitable surfboat or Hobie 18 at reasonable prices, please let me know.

    Regards to all

    Alan
     
  11. GOTTABSOMEWHERE
    Joined: Jul 2008
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    Location: ST LOUIS MO

    GOTTABSOMEWHERE Junior Member

    Hobie/dory/tri

    Hey AUSSIEBUAHMAN



    See my pics with 18' HOBIE and DORY lashed inside with "A" mast
     
  12. lane
    Joined: Dec 2005
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    Location: Austin TX

    lane Junior Member

    Vitamin Sea

    How does she sail, this J24/H18 trimaran?
     
  13. bill broome
    Joined: Jul 2008
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    Location: sydney

    bill broome Senior Member

    don't listen to these people, they are the same ones that said 'an elephant can't fly!' for the same reason, too, and then dumbo came along and showed them that an elephant can fly. hah!
     
  14. Delane
    Joined: Apr 2005
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    Location: Okinawa, Japan

    Delane Senior Member

    J24/h20

    Hello Lane,

    She sails great and so far have hit 10 knots on a reach in about 17 or 18 knots of wind. Will soon finish fabricating an articulating bow sprit and try an symetrical spin.

    Laters,
    D
     

  15. lane
    Joined: Dec 2005
    Posts: 22
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    Location: Austin TX

    lane Junior Member

    Hobie 18 based Tri

    Hey Delane,
    Glad you tri is on the water. I should have my Hobie 18 based Tri on the water in February. With 16 ft of beam, she is VERY stable and gives a lot of walk around room on the tramps. Will post pics soon.
    Lane
     
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