I would consider not putting the foam back in. One of the reasons your boat
floor rotted was probably that the foam trapped water. I completely left
mine out and yes, my boat will sink now if flooded. But I boat in SE lakes
that are flooded rivers so it's hard to get more that a thousand feet or so
from a shore. Some other alternatives I've heard of are empty liter soda
bottles with the caps glued on and sections of those foam floaty noodles
kids play with in pools. I also added drain holes at the rear of each of my
stringers so that water that got under the floor could drain out. If you
previously had a foamed filled floor you probably do not have drain holes.
Manufacturers mistakenly thought that by filling the areas under the floor
with closed cell foam there would never be any water under the floor. You
saw how wrong they were. Given enough time water will get anywhere in a
boat.

If you really want foam I believe US Composites has the two part foam mix
that is used under boat floors. You make a 1 inch hole in the floor to
access each section then pump the mixed foam into it. You want to put a
fairly accurate amount that will fill but not drastically overfill. You want
to entirely fill the compartment. If it gets a chance to expand too much it
will lift your floor. You will need to do some measuring to calculate the
volume of each area.

"moose34" wrote in message
oups.com...
hi all. I'm in the process of replacing the rotted out flooring on an
'85 Glastron CVX-18 and I have a foam question. The foam that was
under the floor was waterlogged and came out in pieces. I know I'm
supposed to use closed-cell foam, but what does the foam actually do?

is it for bouancy? sound deading? space filler?

One marina told me to use pour in foam, and another said just to use a
couple cans of spray in foam because it's just for sound deadening
anyway. which is the correct way?

I'm new to boat repair, but not to boating. ideas or thoughts? Thanks
in advance!

-Guy
(photos of progress thus farcan be found at-
http://www.gmoose.com/gallery/view.php?gallery_id=21)