Conference unifix::sailing

    My wife, who runs a part-time reupholstery and drapery byusiness gets
    it from her suppliers in Mass. This is the flexible stuff - she made my
    cockpit cuishons with this stuff inside. I'll ask her.
    
    Bill
    

    In the UK you can purchase aerosol cans of polyurethane foam that can
    be sprayed into the cavities, where it expands and solidifies. The
    expansion is about 30:1, and it is both of closed-cell and
    rot/water/air/insect and everything else proof. As it also follows the
    contour of the space into which it is injected, it gives very good
    results. It can easily be carved/cut/sanded etc, and generally is
    magic.
    
    The stuff is used normally in the building renovation business and
    similar, and is also extensively used as a duct sealant around cable
    entries into buildings - so should be easy to get in the US.
    
    Hope above is of help,
    

    A two part chemical foam specifically for boats is sold in many boat
    shops. I bought it from Jamestown Supply in Rhode Island. You mix the
    stuff, and pour it into a cavity where it expands and solidifies.
    
    I have used a lot of 'goo' in various boat jobs, but never anything as
    awfull sticky and messy as this foam. The only good part is that after
    it hardens you can scrape the stuff off, but avoid al all costs even
    thinking about scraping or wiping any of it while its still soft.
    
    I used some in one of my sea kayaks. While pouring it into the cavity I
    dropped my most favorite putty knife into the mess. Gone forever. Ive
    also used it under the deck and in the end compartments of my steam
    launch.

A bit of caution is needed when using poured foam. Be sure it can expand 
freely. It can/will develop considerable pressure if confined. 

    Thanks for all your advice.  I'm not quite ready to put the foam in yet
    but I'll keep it in mind when I do.

    Mark Finlayson
    

    Just a nit...the two part foam in place stuff is not closed cell.  It is 
    urethane which is open celled.  Still used for marine flotation though.
    
    Brian

    I think there are two kinds of two-part foam - open- and closed-cell.
    Closed-cell has less buoyancy per unit volume, but is obviously more
    reliable in an open-sided compartment, especially for something like my
    tender which is regularly left in the open. I use the closed-cell kind
    in my dinghy - stood it on end, lined the inside of the thwart with
    polythene sheet (so I could get the thwart back out again afterwards
    :-) - it sticks like... well, supply your own simile), and poured the
    mix. 
    
    Only two real problems - it is next to impossible to get the quantity
    right, so that it just fills the gap and doesn't overflow (could be
    dangerous if not enough space left to allow the overflow to come out,
    and until you have seen this stuff go it is difficult to believe it!
    Don't expect the excess to come out of some small inspection hole - by
    the time it has expanded that much, it is becoming too rigid to flow
    freely) and you have to mix it quickly and get it poured! 
    
    I have had to cut out some areas of my buoyancy recently for repair
    work, and there are obvious signs that the mixing was not completely
    uniform. However, that seemed to result in just some hard spots in the
    cured foam. Cutting it was fairly easy with a sharp knife, and I was
    able to do it in such a way as to be able to slot the pieces back in
    again afterwards like a jigsaw. Because the foam is rigid when cured,
    this worked OK, with the thwarts back on top to secure it.
    
    Oh yes - the fumes given off during expansion and curing are fairly
    toxic - definitely an out-of-doors job.
    
    - Brian