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Thread: Keel/hull build technique

  1. #1
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    Default Keel/hull build technique

    I have a quick question about how modern cat hulls and keels are made. Sorry for posting this here in the design forum, since this is more of a building question. But this seemed like the best place to get an answer to my question here at MH4Us.

    When I was a yacht broker many years ago, selling Caliber and Sabre monohull sail boats and DeFever trawlers, I learned that the standard way that a fiberglass hull or keel was made was by molding the two halves (port and starboard) separately then joining them, usually with epoxy or some other industrial "glue". This was invariably followed by a GRP "tape" running the length of the glued seam connecting the two halves of the keel or hull and covering the glued seam.

    Is this technique unusual for modern catamarans?

    Thanks

    - BH

    .

  2. #2
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    Default Re: Keel/hull build technique

    I doubt it's unusual. It would be difficult to do a proper fiberglass layup in such a narrow mould, as a keel would have, so I'd bet they'd all be like that (built in halves). I have seen FP keels with a seam, but don't have any experience with others.


    Cheers.
    Paul.

  3. #3
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    Default Re: Keel/hull build technique

    Quote Originally Posted by quickcat49 View Post
    I doubt it's unusual. It would be difficult to do a proper fiberglass layup in such a narrow mould, as a keel would have, so I'd bet they'd all be like that (built in halves). I have seen FP keels with a seam, but don't have any experience with others.


    Cheers.
    Paul.
    Thanks Paul.

    Yes, they are indeed built in halves. But monohulls lay a strip (called a "tape") of GRP over the seam. Are you saying that FP usually leaves their seams exposed?

    - BH

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  4. #4
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    Default Re: Keel/hull build technique

    No, I can't speak as to what they usually do. The one I saw damaged was split at the seam. I don't know if they had a strip of tape or not, but if so, it wasn't strong enough to do the job for this particular grounding. I think in general, for Fountain pajot, the keels are made to break-away. I don't think it would endanger the boat if were split.

    What is the basis for your question? Do you have a problematic keel, or are you planning a purchase?

    Cheers.
    Paul.
    Last edited by quickcat49; 14th November 2015 at 01:19 AM.

  5. #5
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    Default Re: Keel/hull build technique

    Quote Originally Posted by quickcat49 View Post
    No, I can't speak as to what they usually do. The one I saw damaged was split at the seam. I don't know if they had a strip of tape or not, but if so, it wasn't strong enough to do the job for this particular grounding. I think in general, for Fountain pajot, the keels are made to break-away. I don't think it would endanger the boat if were split.

    What is the basis for your question? Do you have a problematic keel, or are you planning a purchase?

    Cheers.
    Paul.
    I recently discovered that both of my own FP keels have exposed seams. One of them split along almost its full length having experienced no grounding capable of generating anything even close to enough force to cause that to happen. There is no other damage of any kind to the keel. Once the paint and growth was sanded, we observed that it is perfectly smooth and fair with no cracks or dings or other evidence of coming into contact with anything more than the silty mud that makes up almost the entire Chesapeake Bay. It appears that my keels were simply not built to withstand much at all.

    I have repaired both keels now with a proper GRP layup according to instructions provided by FP. They are now quite solidy protected from future separation. But the question arises ...if this factory-reccommeded fix solves the problem, why did they not build it that way to begin with?

    -BH

    .

  6. #6
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    Default Re: Keel/hull build technique

    Sorry for your troubles. It seems corporations will do anything to save a buck, or to get yours.
    I don't have any more useful information regards FP Keels, but will watch this thread with interest.
    I'm glad you now have it fixed. Enjoy...

    Paul.

  7. #7
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    Default Re: Keel/hull build technique

    And thanks for your replies, Paul.

    Peace

    - BH

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