New Beams for my A Cat

Discussion in 'Multihulls' started by Tinkersailor, Apr 12, 2009.

  1. Tinkersailor
    Joined: Dec 2007
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    Tinkersailor Junior Member

    I have a late 90's A cat which is going on a carbon diet. The new beams have prompted a configuration change so here are the questions.

    1) How far back should the main beam go?

    2) What is the normal hull cant angle?

    3) Once I cant the hulls where do I measure the centerlines of the hulls so I don't end up toed in or out? Do I use the static waterline plane as the center of rotation?

    The static hull immersion will no longer be symmetric. Should this impact my alignment decision?

    Leigh
     
  2. TTS
    Joined: Jul 2007
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    Location: New Hampshire

    TTS Senior Member

    First, what is your a-cat? Second, post this same message through these 4 links. There are many builders, sailors and designers on these sites who regularly modify their boats for better performance. On this site, try reaching out to Retired Geek who designed the LR2/LR3. Hull cant is usually between 4-7 degrees. Mine are canted at five. You need to remember that B-Max is 7'6", so you will be changing the beam mounts at the same time.
    http://www.usaca.info/
    http://www.catsailor.com/forums/ubbthreads.php?ubb=postlist&Board=31&page=1
    http://www.catsailor.com/forums/ubbthreads.php?ubb=postlist&Board=1&page=1
    http://groups.yahoo.com/group/LR2ACATS/
    Lars Guck of GuckInc is another person to contact. He is probably one of the best in the business of working on all performance sail boats, a-cats especially.
    http://guckinc.com/
    lars@guckinc.com
     
  3. Tinkersailor
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    Tinkersailor Junior Member

    Thanks Tom,

    It is a Geugeon (did I spell that right?) brothers design and it was very well built although a little heavy for todays standards at around 200lbs. I think I can get it down quite a bit by going all carbon beams and rig as well as new foils.... the origional stuff was heavy.

    I did post about it some time ago with pictures but can't seem to find my post now.

    Leigh
     
  4. TTS
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    TTS Senior Member

    It is Gougeon, almost right. You will loose quite a bit of weight with the changes you are making. What mast, beam and boom are you going with? I guess I should ask the same about the foils. I am assuming you are switching to a 30' carbon stick from the 27'1" aluminum one. I had a Cal Fuller woodie for a short time and a strange Auscat from the late eighties that I sailed twice and resold. Good luck with the conversion and let me know if there is anything that I can do to assist you. You might also track down Fred Smith who is up in your area somewhere. I think he is in Toronto though. He has been sailing in the class since the late 60's and is part of the LR2 project. I will send you his email if you would like.
     
  5. ThomD
    Joined: Mar 2009
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    ThomD Senior Member

    I know the Gougeons stopped selling their cat plans a while back. Did they get preserved, can they be downloaded? Or for that mater are there other similar stressform plans out there?
     
  6. Tinkersailor
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    Tinkersailor Junior Member

    I know Fred thanks. He helped me with the history on the boat some time back.

    I have plans for the boat (from a different source).

    So far I have a main beam (carbon) less than half the 14lbs that the aluminum one weighed. But it will need a striker.

    Foils will be 63-412 I think (or a variation) I will mould them.

    No decision on mast or sail yet.

    Here are some pictures:
     

    Attached Files:

  7. TTS
    Joined: Jul 2007
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    TTS Senior Member

    Nice looking with West and fairing compound on the bow. Some of the a-cats use striker-less main beams and others do not. I think that Fred uses a striker on his Hall Spars beam. I am looking to replace my aluminum beams with carbon this year. do not know whether I will go with Hall, CTS on forte yet. The rudder foils are my first job. I own Fred's old Boyer after rebuilding and selling an older Waterat.
     
  8. Tinkersailor
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    Tinkersailor Junior Member

    I think it was actually some glass and polyester resin....Fortunately not of my doing (and gone now). The bows have already lost some weight (raked back dreadnaught style now) and I think the main beam is going back about a foot. The decks forward of the beam will be removed as they have a heavy sheer clamp under them and I will lower the new ones toward the bow. I figure I can probably take 8lbs out of each hull if I am careful.

    I have already had a quote for a strikerless main beam at $650 US. Does that sound about right?

    Still looking for advice on the alignment question. The design waterline I see on my plans shows the transom clear of the water and the bow corner just touching the water. I wonder if this is the boat or boat and crew waterline.

    Leigh
     
  9. TTS
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    TTS Senior Member

    $650 does seem about right. I suppose you could shop around and you might find $50-75 savings, but you might not either. Are you pulling out the bulkhead beneath the main beam and re-set the bulkhead under the new placement?
     
  10. Tinkersailor
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    Tinkersailor Junior Member

    With the deck off I will rip out/move whatever I think needs doing (done this before on a Tornado). I am thinking about bonding the new beam in. Scary if i get it wrong though. Thinking strikerless to save weight.

    I will also pull the old CB case and repair the holes.

    Leigh
     
  11. TTS
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    TTS Senior Member

    I am rebuilding a tornado right now. Most of the issue is in the beam boxes. Quite a few A-cats are bonded and it seems to work out great for them. It stops any flex from the attachment points so you end up with a stiffer platform. You could set the beams and allow the epoxy to set and then remeasure before laying carbon and fairing over the beams.
     
  12. CTMD
    Joined: Dec 2007
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    CTMD Naval Architect

    Leigh,

    I posted some answers over at catsailor. Going to a strikerless beam will be heavier then a well designed beam with composite striker. So if you're looking to save weight keep the stricker just make it carbon.
     
  13. bad dog
    Joined: Apr 2009
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    bad dog bad dog

    Does anybody know of a complete history of A cat development - with photos of all mainstream changes Mk1 to 5, as well as a few of the weird and wonderful experiments along the way?

    Bad Dog (good cat)
     

  14. wjvining
    Joined: Apr 2009
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    Location: CT

    wjvining New Member

    Mast and sail

    Leigh,
    I've got a repaired carbon Hall mast that you might be intereted in. I've also got a sail that would be a good addition to your project. And I'm going to put curved boards on my boat,so the daggers and trunks are available too.

    Im in CT and you would need to either come pick up the mast or arrange to have it delivered.

    If you come down for any of the summer Acat races, you can pick it up then.

    I used Forte beams on my Acat, Forte has the best value on carbon tubes, and I wouldnt use 5200 to bond the beams in, use a thickened epoxy. There are several around, but I used a 2 part thickened epoxy from Gougen, Proset 176/276, you'll need to borrow/buy a 2 part gun, I will lend you mine if you need it. The gun is pricey, $100 at least.

    you can email me at wjvining at yahoo.com
     
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