Fill hull with foam?

Discussion in 'Fiberglass and Composite Boat Building' started by wrbowcal, Apr 3, 2010.

  1. wrbowcal
    Joined: Apr 2010
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    Location: Crowsnest pass, Alberta

    wrbowcal Junior Member

    Hello,Im new to this site and I have learned alot from the posts.I have a 1978 bayliner 2750 and have the floor,stringers and ribs out and it was a rotten nightmare everything was replaced years ago and it was done poorly now I have to fix it.Can I fill the hull with foam to the bottom of the floor after I repair? I noticed were the foam was that I removed the hull was shiny and looked in good shape.This cabin design has no place for the water to go it does not go into the engine bilge compartment from the cabin and I was thinking of making the floor water tight and tap a hole at the bulk head on the floor to drain any water in the cabin to the engine compartment,would this be OK.[​IMG]
    [​IMG]
     
    Last edited: Apr 3, 2010
  2. Herman
    Joined: Oct 2004
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    Herman Senior Member

    I do not like PU foam in any floating object. If there is a path for the water to travel into the foam, the foam will become water-logged, your boat will be heavy, and you will have to digg it all out again.

    I prefer a situation where you can drain water that has entered the boat. Either by (automatic) pump, a drain plug which will be opened after getting the boat on land (mainly used in dinghies, Laser comes to my mind) or even by good old sponge.
     
  3. wrbowcal
    Joined: Apr 2010
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    Location: Crowsnest pass, Alberta

    wrbowcal Junior Member

    I have a Atwood pump and will put it on the hull near the bulk head and design so water can flow to that area.
     
  4. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    You can fill the cavity with polyurethane foam, but only the 2-components type. Foam from a can reacts with moisture: in a closed confinement it rapidly uses the available most air, so only a skin up to 1" thick hardens out and shields the still liquid core from absorbing more moist air.

    With the 2-component type you need to know the approximate volume and mix the corresponding quantity. If you use too much, pressure builds up and raises your floor!
     
  5. alan white
    Joined: Mar 2007
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    Location: maine

    alan white Senior Member

    Try two liter plastic bottles. Cheap, inert, long-lasting, won't stick to anything, recycled product, low tech (anyone can do it, even babies), easily obtained, fits odd spaces.
    Also incredibly redundant. Leakage of one bottle hardly matters and doesn't affect the rest of the bottles.
    The only reason to use foam instead would be to either add a structural componant or to completely fill the cavity due to the cavity being marginal in volume. Otherwise, foam is inferior to bottles.
    Welcoming comments...
     
  6. rasorinc
    Joined: Nov 2007
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    Location: OREGON

    rasorinc Senior Member

    You can use stryofoam billits cut to any size and shape. These will not absorb any water but need to be protected from the sun. Also compatable with epoxy
     
  7. wrbowcal
    Joined: Apr 2010
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    Location: Crowsnest pass, Alberta

    wrbowcal Junior Member

    Thanks I just looked at some 2 part foam the other day and it sats it wont soak water.I want to fill the front part of the boat only with the floor off and cut the foam down to the stringers and ribs then add the floor do think this would work?[​IMG] This all tore out now.
     
  8. wrbowcal
    Joined: Apr 2010
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    Location: Crowsnest pass, Alberta

    wrbowcal Junior Member

    Hey thats not a bad idea.Will consider.
     
  9. wrbowcal
    Joined: Apr 2010
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    wrbowcal Junior Member

    Would styrofoam SM you know the blue 2" board work. I have some of that kicking around I would just have to cut to fit.I wonder if PL premium or liquid nails would glue the cut pieces together well[​IMG]
     
  10. alan white
    Joined: Mar 2007
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    alan white Senior Member

    I do it. And I am quite fussy about safety and fit and finish. The truth is, nobody here at least has yet come up with an argument against using bottles.
    Here in the USA, a 2000 lb boat costs about $40.00 to float using bottles at the going rate of 8 cents each!
     
  11. wrbowcal
    Joined: Apr 2010
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    Location: Crowsnest pass, Alberta

    wrbowcal Junior Member

    I will go that way if I have to do work on the hull in the future it will save time and money thanks.
     
  12. rasorinc
    Joined: Nov 2007
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    rasorinc Senior Member

    The U.S. Coast Guard does not like plastic bottles. Thats all.
     
  13. alan white
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    alan white Senior Member

    No doubt due to aluminum-capped ones in the past. The money you save using bottles will buy a lot of other safety gear---- an extra radio, for example, or a GPS, or a depth guage, etc..
     
  14. brokensheer
    Joined: Jun 2009
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    brokensheer Senior Member

    what if the plastic bottles were filled with foam? keeping the water off them
     

  15. tinhorn
    Joined: Jan 2008
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    Location: Massachusetts South Shore.

    tinhorn Senior Member

    I beg to differ. I bought a 12' Snark hull that must have weighed 250 pounds--styrofoam with a plastic shell. Have also pulled Styrofoam out of small boats that felt as heavy as concrete.

    I think this is a clever idea. After I recently read the tip here, I started accumulating small soda pop bottles to stick under the seats of a couple dinghies (through some round access plugs that I'll need to install).
     
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