Foam bouancy

[dowdy]

Just putting some ideas together before we start building on wednesday,what is everyones thoughts on filling all the underfloor voids with expanding foam,seems to big thing in states,anyone seen the ad with the boat cut in half and both bits still float?

[Polwart]

Dory

[Nos4r2]

Waterlogged foam

[Dirk Diggler]

Boston Whaler....... underfloor bouyancy is a great idea, but you'll really regret it if you ever have to do a repair!

[C-NUMB]

Only 100% closed cell foam that wont suck water in any conditions would be worth considering IMHO. But even that would add weight and cost. Don't think expanded foams fills that criteria. XPS in theory would be OK, but that can't handle polyester resin or other solvents so its not really an option.

A rib wont sink easily even if damaged so I would not do it on a rib.

[Anchorhandler]

I toyed with the idea of filling all the voids on our previous boat with hundreds of ping pong type balls....admittedly you would lose some if you damaged the hull but short of ripping a big chunk out it It should of provided quite a lot of reserve bouyancy. Lightweight and cheap too (if you can source a bulk load of them, which wasn't an issue for me as we use a similar think in industrial oil separation machinery)..... It a was a French built sport fisher though and didn't have the inherent safety of a rib. I sold the boat before I did anything about it...

Simon

[Nos4r2]

Originally Posted by C-NUMB

Only 100% closed cell foam that wont suck water in any conditions would be worth considering IMHO. But even that would add weight and cost. Don't think expanded foams fills that criteria. XPS in theory would be OK, but that can't handle polyester resin or other solvents so its not really an option.

A rib wont sink easily even if damaged so I would not do it on a rib.

A lot of sports/fishing boats have it. It still waterlogs-it's just a matter of how long it takes.

[C-NUMB]

Originally Posted by Nos4r2

A lot of sports/fishing boats have it. It still waterlogs-it's just a matter of how long it takes.

Think we are saying the same thing. I am not aware of any PU foam that would not get water
logged by time, and then its a "no can do" situation. The foam also might to get loose from the surfaces by time, that's not funny either.

XPS believe will not get wet like EPS or PU, but can as far as I know not be used as expendable foam( + the resin issue) so guess it has not been used in marine industry that much.

[martini]

My Halmatic's full of closed cell foam. Looks like it started out as 4" thick sheets which were then cut and shaped to fit in between stringers etc. When I pulled up the deck 13 years later the foam still hadn't absorbed a drop of water

[dougal_22]

my river cruiser has a foam filler between grp sandwhich lay up on the cabin roof and gun whales, granted untill i purchashed the boat it was very neglected but it has got wet and is proving an utter pain in the rear to get dry.