Question on foaming spaces.

Discussion in 'Fiberglass and Composite Boat Building' started by Skua, Apr 27, 2014.

  1. Skua
    Joined: Apr 2013
    Posts: 142
    Likes: 5, Points: 18, Legacy Rep: 73
    Location: Hunt's Pier WW NJ

    Skua Senior Member

    What are the cons of using 2lb density floatation foam in these under deck spaces? Plan is to seal each chamber, using same materials in reconstruction, (glass and epoxy). Areas involved have never shown water ingress, exept from failed shower sump, which rotted out supports and framing.
     

    Attached Files:

  2. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 473, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Foam filling wooden spaces is problematic at best. Why not just seal them up tight and put in a deck plate so they can vent when the boats not in use.
     
  3. kwhilborn
    Joined: Apr 2014
    Posts: 16
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Toronto

    kwhilborn Junior Member

    I am no expert, but I know I have read some foams (especially Spray) can start water retention after a decade or so. If you are building a vessel you hope your grandchildren might sail someday this might be a bad thing.

    Boat manufacturers under 20' must meet a positive flotation requirement, and that is a good reason to have foam. Even a capsized vessel will float until rescue. Safety first.

    There are good block foam options if you do your research, but I'd avoid most spray foams if you like the idea of boat longevity.
     
  4. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,006
    Likes: 356, Points: 83, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    4lb density is pretty well immune to water absorption, by many reports, but the weight could be an issue in some boats.
     
  5. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 473, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    I only spec 5 pound foam for these types of applications and prefer they are encapsulated or bagged to prevent issues. A 5 pound foam then becomes a structural element if desired.
     
  6. Ike
    Joined: Apr 2006
    Posts: 2,259
    Likes: 194, Points: 63, Legacy Rep: 1669
    Location: Washington

    Ike Senior Member

    My method is to use block foam (not two part pour foam) and bag the foam in plastic sheeting.This prevents the foam from being exposed to water, and chemicals that can dissolve it, and you can then use simple cheap polystyrene foam which can be bought for a few dollars in large sheets. All the big box home improvement stores sell it as insulation foam. However do not use Styrofoam. It has a much larger cell size and is subject to breaking up from shock and vibration. So no water absorption and no foam deterioration.

    You then cut it to size to fit the space. [​IMG]

    see http://newboatbuilders.com/pages/SeaRay190.html

    PS. The pink piece never gets wet and supports the sole. So I didn't page it, but who knows I may regret that. But it is easily replaced.
     

  7. Skua
    Joined: Apr 2013
    Posts: 142
    Likes: 5, Points: 18, Legacy Rep: 73
    Location: Hunt's Pier WW NJ

    Skua Senior Member

    This picture was pre tabbing on the deck supports. It is all epoxy and glass to the deck line . The bottom of the deck is glassed with 1700 triax and epoxy, and will be glued down with milled fibre and epoxy. The idea was to help support decking and to add non floodable chambers, in case of holing. My area has lots of shoaling and debris, at the moment. Not that I paln on running onto anything.:p
     
Loading...
Similar Threads
  1. Anthony212
    Replies:
    6
    Views:
    293
  2. Midday Gun
    Replies:
    5
    Views:
    362
  3. atengnr
    Replies:
    46
    Views:
    904
  4. fallguy
    Replies:
    2
    Views:
    281
  5. fallguy
    Replies:
    5
    Views:
    491
  6. Andrew Courtney
    Replies:
    3
    Views:
    453
  7. JohnMarc
    Replies:
    7
    Views:
    533
  8. Bullshipper
    Replies:
    7
    Views:
    738
  9. GP1998
    Replies:
    17
    Views:
    2,024
  10. freddagg
    Replies:
    15
    Views:
    1,058
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.