30 Yr old poured foam blocks. Dry. Sound. Still Usable?? Pics

These are the 2 large poured flotation blocks Hurst stuck in the middle of the boat, boxed and glassed to the sides.
The plywood was rotten, the blocks soaked. I cut them out to replace the underlying decking and have since decided that I didn't like where they were at in the first place. Right in the way.I would like to reuse them in another place, under the front top deck, but have read that pourable loses it's bouyancy afterwhile.These things are 30 yrs old. I've had them in my shed for over a month now, drying. Can they be reused?
I would like to reshape them and use them to fill the void between the main deck and the bow fishing deck.I plan to use plenty of foam above deck,just not in the bulky shape these are in. I've already
bought 2 sheets of 1/2" insulating foam, (EPF) as well as a 16 lb kit of 2 lb pourable. (2 Gals).
I plan to fab a 2 sided 4" X 4" "L" , and glass it to the deck and side right at the chine, and pour it with the
2 lb pourable. My main question is, since they are dry, and feel solid, can I reuse them? I could save a few bucks
if I could. Siding insulation foam is cheap, pourable aint. Thanks, KR

Re: 30 Yr old poured foam blocks. Dry. Sound. Still Usable?? Pics

I just purchased some 20+ year old foam from a guy for 1/3 of the price of pour foam and will use it along with original foam salvaged from my boat for floatation once the repair is complete. The foam I purchased was stored outside and had about a 1/4" dead layer on top but under that it is fine.

I questioned the integrety of the original foam in the boat so after cutting a bunch of it to square it up for easier use, I dunked it and watched for air bubbles and their were very little so I say its good. The cells that were cut are now open and will hold water but not enough to be a problem.

I would make sure that the siding insulation is fuel resistant.

Re: 30 Yr old poured foam blocks. Dry. Sound. Still Usable?? Pics

No, do not reuse them. The reason you are trying to dry them out is because they failed and started to absorb water. The foam is supposed to be closed cell, but over time, it breaks down and becomes open cell (like a sponge) and soaks up water. It is very hard to get the water back out. And even if you do get the water out, the next time it gets wet, it will suck it right back up again.

So toss them out, and go buy new foam.

Re: 30 Yr old poured foam blocks. Dry. Sound. Still Usable?? Pics

If closed cell breaks down over time I might reconsider my method also. Just for grins I will ask Jgreer their opinion but I feel comfotable reusing the boats original 10 year old foam and the 20 year old stuff I have as well. One thing I noticed when pulling the foam out of my boat was that the foam pour was not monolithic and water was inbetween the pours (the boat had been swamped).

Rebuilt, how wet was the foam you pulled out? Was it heavy with water or just wet on the surface?

Has anyone here actually seen floatation foam that broke down and absorbed water like a sponge?

Re: 30 Yr old poured foam blocks. Dry. Sound. Still Usable?? Pics

Hopefully this might be of some interest to this thread : http://www.glen-l.com/weblettr/webletters-7/wl55-flotation.html

Re: 30 Yr old poured foam blocks. Dry. Sound. Still Usable?? Pics

Good logic Mark. Out they go. They were very heavy, soaked. Closed cell shouldn't do that. The Lowes sheets go up front,reshaped, under the fishing deck, between it, and the 2nd foward deck. This tri-hull had a small factory fishing deck that topped out well below the gunwales. Then someone added a nice, big, gunwale level deck across the bow. I want to fill this unusable dead space with flotation. Remember, it's a tri-hull. It's hard to reclaim those 3 bow curves into usable storage. But I can still make use of the space. Thanks again. Good stuff. KR

Re: 30 Yr old poured foam blocks. Dry. Sound. Still Usable?? Pics

Thanks gcboat! Very informative link. I'm still in line with recommendations. After he showed all of the calculations, I noted that it breaks down to approx 1 cu. ft per 100 lbs. Not sure I fully understand this, 2 lb pourable supports 60 lbs per cubic foot. I guess after all the densities and other variables are added in it all works to that formula. No matter, I should be able to pull off what I'm trying to get done here. Thanks for the info. KR