new construction steel boat spray foam

Discussion in 'Metal Boat Building' started by mikeny, Jun 4, 2015.

  1. mikeny
    Joined: May 2013
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    Location: Husum Wa

    mikeny Junior Member

    anybody out there know what the current belief is on spray foam or not on steel hull sandblasted primered and epoxy painted
     
  2. AndySGray
    Joined: Jun 2014
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    Location: Cayman

    AndySGray Senior Member

    The caveat is that applying it requires a true professional;-

    It requires a good knowledge of the chemistry vs. the ambient conditions. If it is applied too thick, the heat it generates cannot escape quickly enough and the curing process does not work correctly.

    Correctly done it has awesome thermal properties and sticks like glue.

    Make sure all ducts, boxes and conduits are in place as fitting them after is a pain.
     
  3. mikeny
    Joined: May 2013
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    Location: Husum Wa

    mikeny Junior Member

    Hi Andy what do you think of the ceramic BB's that they put in paint to gain thermal break like math code lizard skin I hate to cover up all the steel


    spraying only one inch of fire retardant foam and then augment with additional insulation inside cabin foam is so messy and I hate to cover up all the steel but I want to do what works the best
     
  4. AndySGray
    Joined: Jun 2014
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    Location: Cayman

    AndySGray Senior Member

    Have no experience on the ceramic BB's.

    I guess the first question is really regions and seasons?

    If the boat is going to need a heater or an airconditioner, you will get massive payback from going big on the insulation, summer day-sailer less so.

    Remember that moisture will condense from a warmer atmosphere onto cooler steel, which is the key benefit of the foam - you could get a similar insulation using e.g. Rockwool, but there is going to be the condensation behind the foam and a nice sponge to keep it against the steel. With the foam, the moist air will never contact the steel.
     

  5. rwatson
    Joined: Aug 2007
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    Location: Tasmania,Australia

    rwatson Senior Member

    I am sure Mr Wiley can provide some ideas, but having seen him cut and fit dozens of foil lined foam sheets, the spray idea could be useful.

    Discussing his strategy, he felt that the foam from the hull would keep the hot air away from the inner steel hull and avoid condensation. My inexperienced gut feel is that you are going to get condensation anyway, albeit reduced.

    Condensation is not really a problem unless it pools. I remember a conversation with an NA that insisted on 'filling in' all the moisture catching stringers on a commercial craft, with an inert tar based compound that directed any moisture to the bilges. During the 3 year inspection, the amount of rust was negligible - which was not the case on the same boat in the previous 3 years, where they had to do major needleblasting and repainting.

    The sprayed foam would have the effect of filling in the pooling places I would expect.
     
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