Crowther karaken 33 - Rigging

Discussion in 'Multihulls' started by parry, Aug 23, 2007.

  1. parry
    Joined: Aug 2007
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    parry Junior Member

    Hi,

    I wish to fit a roached main to this boat. The problem I have is the two backstays dont allow enough freedom of the main. Does anyone know of a roach fitted to this model of tri or think of a reasonably simple solution to change the rigging to allow one?
     

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  2. catsketcher
    Joined: Mar 2006
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    catsketcher Senior Member

    Interesting

    Hello Parry

    I am intrigued by your question. Your Kraken seems to have a maze of stays - one to each beam end and a backstay too. Are you thinking of getting rid of the all five and replacing them with two swept aft sidestays?

    I would need to look it up but I think that the amount of sweepback for sidestays needs to be 30 degrees to act as back stays too. I guess this would place the chainplates somewhere in mid air between the beam ends.

    If the Kraken were a Bucc36 you would just put the chainplates in the float but you may increase the loading on the float stilts too much. I see two avenues.

    A bridle - lead a husky bridle - much like the seagull striker bridle on a cat forebeam from each beam end and up to a point about 3 metres above the deck. The higher the bridle of course the lower the loading. Then increase the size of the remaining sidestay to cope with the higher loading.

    Make a box beam to take the loads. Designing a plywood box beam - your beams are ply box beams is pretty simple cookbook engineering. Work out stability of the boat - use trig to find out the loading on the sidestay. Look up aircraft book (Stress without tears by Bernard Rhodes) and design ply beam to take load with safety factor. SF is a guess. Make strong without getting heavy. Glass and glue onto beams - heavier and harder than option one

    Or look carefully at stilts and increase size of needed.

    The only Crowther of similar period that I know that did this is a 40ft Spindrift cat. It sailed better with the mod

    cheers

    Phil Thompson
     
  3. parry
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    parry Junior Member

    Thanks phil,

    I think I ill look into the bridle idea, it had crossed my mind before I had just never seen it before. Didn't think of a cat forestay. Also trying to find a decent picture of how the farriers get around this problem having their stay going to the center hull. We only have a couple of smaller ones here so im not sure if they use the same principle on their larger boats. The box beam idea is one I hadn't thought of, and not a bad one at that. Gives me two decent options to look into, thanks.

    I just read your post regarding this boat in a different thread. Thanks for the news, always good to hear a bit of history on your own boat. As you mentioned someone has strip planked the bottom in cedar im told, always wondered about that as it wasn't in the pans. I was starting to think i may have the last kraken in exsistance, its been fairly difficult to find out any information on them.


    Thanks again,

    Steve
     
  4. Goth
    Joined: Nov 2010
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    Goth Junior Member

    OMG..... its "Torpid turtle"
    is it the original one?????
    if so, WOW..... its still alive, well done :)
    it was built in Melbourne......then went to Qld and got the right mast put on it.
    (the original owner ran out of funding building it )

    it was moored at warneet (western port bay) when my dad had his Bucaneer 33
    (Sea spider)

    good to see it again
     
  5. Gary Baigent
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    Gary Baigent Senior Member

    Parry, are the two backstays adjustable, like in runners (which they should be)? - then if adjustable you shouldn't have any trouble with the stays fouling the mainsail roach leech, you just have to free the leeward one off. I don't see any permanent backstay, just a main halyard to clew position on the boom.
    It is an old designed rig and Lock didn't really get the masthead setup right, better to go to fractional, rotate the mast, two adjustable angled aft shrouds and two runners, just imo.
     
  6. Goth
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    Goth Junior Member

    the original mast set up, was fixed back stays, you might be able to move them to the floats (right behind the rear beam, the kraken's had a problem with the beam riser's....they tend to fail if under to much load) (just be carefull)
    this is how kraken's trip over there floats.

    hope it help's
     
  7. Gary Baigent
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    Gary Baigent Senior Member

    There are advantages of having the runners attach to the float after beam junction and make use of the trimaran platform's wide beam - but if you are worried about strength in that area, you could mount the running backstays (a la monohull) each side of your main hull stern area ... but you will have to remember to tighten one, free the other every time you tack or gybe. Becomes automatic, not a problem.
     
  8. oldsailor7
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    oldsailor7 Senior Member

    Goth. Your dad wouldn't be Gerald Tate by any chance, would he. ???
     

  9. Goth
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    Goth Junior Member

    ummmm yes it is..........small world isnt it ??????
     
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