Keels and Keels Again!

Discussion in 'Boat Design' started by D'ARTOIS, Feb 9, 2006.

  1. explorer2203
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    explorer2203 New Member

    Yes indeed! It wasnt my yacht by the way - I was one of the crew. Just to be clear on that LOL

    Craig
     
  2. tunnels

    tunnels Previous Member

    Who ever concieved that idea for attaching a keel of that weight to a boat want his nuts chopping off . Hes a idiot a complete nutter !!
    :confused:
     
  3. powerabout
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    powerabout Senior Member

    Tunnels
    Every major 'yacht designer' has used that method even your fellow countryman Mr Farr
     
  4. tunnels

    tunnels Previous Member

    You just reminded me of the evey first of the Farr 38s They had a long keel stub moulded in with the hull and yes it was nearly the same sort of mounting of the lead to the stub But they were all changed very quickly .Didnt fall off but the glass used to slowly give up and leak water into the boat .
    A boat builder boat designer friend of mine made the new wooden floors for the first 3 boats that were made and changed .After that the whole system was changed rather quickly!! Boy that was a long time ago . Had forgotten about that !!. guess some one wanted to reinvent the wheel again !!:D
     
  5. ancient kayaker
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    ancient kayaker aka Terry Haines

    Have to admit, that was my first reaction too, but I can only think of 2 ways of attaching a keel, one would be the cantilever method used for the Cynthia Woods and the other would be to have a stub on the top of the keel fitting into a socket moulded into the hull.

    The first method is by far the simplest and cheapest, the second is rarely used. A third method is to have the keel a permanent part of the hull, OK while the boat is in the water but there it has disadvantages out of it.

    The cantilever attachment is satisfactory if done correctly. However you attach the keel, if the boat runs aground and damage ensues there will be issues. With multiple groundings and inadequate inspection and repairs the issues can be fatal.
     
  6. Chris Wren
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    Chris Wren New Member

    Lifting keels

    I am trying to find what was supposed to be in place to lift the centreplate on a Ted Hood 53 ft 1969 design.
    Anyone have any information please?
    Regards,
    Chris.
     
  7. Earl Boebert
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    Earl Boebert Senior Member

  8. Boston

    Boston Previous Member

  9. Tad
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    Tad Boat Designer

  10. upchurchmr
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    upchurchmr Senior Member

    Gentlemen, I just found this thread, but have a few comments about the comparison to Airplane wings. All airplane wings are bolted on in one way or another. Wings that are "just bolted on the side of the fuselage" include the F-22, F-35, F-16, F-18, F-2 (Japan copy of F-16), the Tornado (European fighter), and at least 3 Russian fighters I know about and thats just the ones I know about personally. And yes, those bolts are big XXXXing bolts even in the little aircraft (fighters). The real difference is the stunning amount of money spent to prove the strengths of the materials used (to national standards) and the equally stunning amount of money to design, analyse, and test the structure. You don't really believe aircraft are expensive due to $900 toilet seats, do you? 10 bolts @$500 each per wing is just a small reason for aircraft costs.

    I'm in the structural design group for Lockheed (one of many people).

    It should be relatively easy to attach a keel properly and would probably not affect performance enough to notice, since the joint is at the bottom of the boat. If you did it aircraft style you would make a boat just for test, set up a bunch of hydraulic actuators to simulate loads at sea, including occasional grounding, then run the test for 2 to 4 lifetimes of useage. None of you could afford the boat after that and it would be out of date by the time you finished. Assuming no one made a mistake (Murphy or being human) and the test failed and you started over again.

    Probably scantling rules could be improved, but controlling the material strengths as built at the factory would be very difficult without someone inspecting and testing the work.

    Ignore aircraft comparisons, it is a completely different life.

    Marc
     
  11. powerabout
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    powerabout Senior Member

    Yes easy to calculate and control in a homogonous material like metal
    now try it with a material that you mix up in a pot and use day to day or use pre preg that is new one day and not new when you use the last bit.

    and then theres the old...you need a license to build a plane, what do you need to build a boat?
     
  12. Boston

    Boston Previous Member

    Ya sounds like a perfect storm of errors, my condolences to the families.
    Thanks for the link

    B
     
  13. MikeJohns
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    MikeJohns Senior Member

    Attached Files:

  14. Doug Lord
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    Doug Lord Flight Ready


  15. MikeJohns
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    MikeJohns Senior Member

    Thanks Doug, but it's relevant to this thread too.

    Another thread that's interesting wrt long strut and bulb keels that seems to have gone largely unnoticed is here:

    http://www.boatdesign.net/forums/sailboats/new-test-data-keel-loads-36223.html

    Since there was fortunately no loss of life in Ramblers case (but they were lucky) we will be unlikely to see any public reports. But it would have been interesting to see the design assumptions with regard to fatigue loading. Low factors of safety make highly stressed structures prone to failure from small imperfections.
     
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