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)