Floatation question

Discussion in 'Fiberglass and Composite Boat Building' started by tsmart, May 28, 2008.

  1. tsmart
    Joined: May 2008
    Posts: 11
    Likes: 1, Points: 0, Legacy Rep: 20
    Location: Lenoir, NC

    tsmart Junior Member

    I have a fiberglass boat project I'm working on - got a Couple Questions;

    1) Did '70ish model Sunfish Boats come w/ open cell floatation foam inside the hull?

    I done some inside the hull inspection on the rear end of mine.... and there's some foam that looks like a Styrofoam cooler (white, closed cell foam). Seems some ants invaded the white foam, and have eat it up quite a bit.... and nested in it - so I am removing it to add new foam..... But, the white foam was held in place by some "yellow" foam.... which looks like the spray insulation foam (open cell) which you can get at Lowes. The yellow foam, was retaining water - thus I am replacing it as well (it's going to be a real task, I can tell). I haven't gotten into the front of the boat yet to inspect that end (and I'm dreading it).

    2) I though boat builders used closed cell foam, so it wouldn't absorb water. Any thoughts? or does the closed cell foam break down over time, then absorb water? Trying to figure out why it's waterlogged (besides the fact of a small crack in the hull, that I'll be fixing).

    3) Can anyone recommend any "new type" yellow foam, to ahdhere the white floation blocks into place (that won't become waterlogged over time)?

    Thanks,
    Troy

    PS - I will also have some glassing questions later:D
     
  2. dmcld77
    Joined: May 2008
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    Location: California

    dmcld77 New Member

    Foam

    I always use high expansion liquid foam. Stand the boat on end and pour it in and it will immediately react and turn into waterproof foam and expand until it comes out where you poured it in. It will fill all the nooks and crannys and is extremely rigid. I have used it to stop the flex between outer bottom and inner plywood floor on a 18' Tahiti with 3 100hp mercs on it.
     
  3. tsmart
    Joined: May 2008
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    Location: Lenoir, NC

    tsmart Junior Member


    Do you have a link or name for the foam (so I could google it)?

    Did you say 3) 100 merc's?? I bet that sucka will scatt!:eek:

    Thanks,
    T.
     
  4. dmcld77
    Joined: May 2008
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    Location: California

    dmcld77 New Member

  5. dmcld77
    Joined: May 2008
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    Location: California

    dmcld77 New Member

    T:
    I gues it is really Polyurethane Mix and Pour Foam.
     
  6. tsmart
    Joined: May 2008
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    Location: Lenoir, NC

    tsmart Junior Member

    Good site, thanks for the link... and for your time.

    T.
     
  7. LQT420
    Joined: Apr 2007
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    Location: Connecticut

    LQT420 Junior Member


  8. Herman
    Joined: Oct 2004
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    Location: The Netherlands

    Herman Senior Member

    There is a drawback with polyurethane foam: Although it is closed cell, and watertight, it is not tight to water vapour... Which basicly means that water vapour can enter the foam, condensate, and never comes out again.

    I have inspected many boats with water-logged polyurethane foam. It can be a real pain in the rear.

    Some things that come in my mind:

    -although PU foam has this nasty habit, I still do not know of any other type of pourable foam with similar properties, and better water properties.
    -to prevent water logging, make sure the boat is completely airtight when pouring the foam in. This way water cannot enter as fast as when the boat is leaking from the beginning.
    -In Europe, boats tend to be used longer, so these effects show up more than in USA.

    Use gloves when handling the PU foam. It takes ages to get of your hands.
     
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