just got a 1988 stratos bass boat, noticed some rotten wood on the side where the batteries are,found out foam was soaked on both sides,i removed it ,anyone else have this happen ,if so what kind of wood and foam did you use ?

actually I guess its the bilge foam that was waterlogged, has anyone ever used the foam sheets from the big hardware stores for floatation foam,or do I have to use 2 part liquid foam?

Don't know what to tell you about the two part.  It expands, but how much?  You'll need to know, so you can make a reasonable estimate.  You'll need to have an opening, probably where you pour the two part foam.  That opening allows the excess foam to escape, before it sets up.

 

I'd avoid the white, lightweight stuff they carry at Home Depot or Lowes.  It is not waterproof.  It's fine in buildings where it isn't susceptible to battery fumes, or oil.  But for the innards of a boat, not so good.  You need a marine grade, closed cell foam, for what you are doing.

 

Google "instructions for two part marine foam flotation" or something similar.  You should get plenty of info on how to use it.

The pink foam (4x8) will work so will SOME spray foam as long as its closed cell foam.

FYI "great stuff" foam is open cell and won't work.