Foam Questions
 

I'm putting my order together for all the material on my rebuild. Question I have is how much foam to order and should I go with the 2lb or 4lb? Looking at placing the order with US Composites. Any better/cheaper places to order from?
Thanks,

I've had good luck with US Composites for Foam, fiberglass, resin, etc. Good prices, fast service.

I like the 4LB it will add strength to the structure if needed. You can check this guy out or call him he can set you straight. http://www.mertons.com/Floatation/index.html

Ditto on us composites. 4 pound is definitely structural. 3 lb expands more and is fine for taking up space. I have always ordered it in 5 gallon buckets. Be careful with the cold weather when having it shipped.

Nice thought.

Ditto gchop.

I've used the 4 lb stuff. Its pretty strong all by itself. inside fiberglass walls, it should be stronger than you are likely to need. Just make sure you have vents to allow the foam to fully expand into all corners.

For floatation, use the 2lb foam. You'll get the same buoyancy for half the cost and half the weight. The heavier foams are structural, for use in casting or sculpting applications where durability is more important than weight or buoyancy.
Dave

To re-fill the box stringers with 4lb foam it will take little over 3.5, 1 gallon kits so you will need: 4 kits just for the stringers. 4 gallons of part a and 4 gallons of part b (8 gal's total). Not sure how much to do the outer areas. Just done my sf and make sure you have every thing ready and mix it well then pour fast. You don't have much time once mixed


To meet us coast guard flotation requirements I think they require the 4lb density or less but not sure on all the floatation requirements. Maybe some one on here knows more about the requirements.

I agree with Dave - SeaCraft never depended on foam for strength, it was for flotation only. The original Moesly 21 and maybe the 19 Bowrider, which is the same basic hull as the 20, were built in the 60's prior to the USCG flotation requirement and had NO foam, so they're obviously strong enough without it. Why use the denser foam which will actually provide LESS net buoyancy when the whole purpose of using foam in the first place was to increase buoyancy! The main thing I'd check is to make sure it's closed cell foam, to minimize water retention if it ever does get wet.

From US Composites description of their 2lb foam:

Our 2LB density marine foam is recommended for void filling in nonstructural applications. This product can be poured underneath decks and inside cavities where a lightweight flotation foam is needed to provide buoyancy. This foam has been tested in accordance with U.S. Coast Guard Regulation # 33 CFR 183.114 . This foam is approximately 95-98% closed cell which resists absorbing water, however continuous water submersion can eventually lead to loss of buoyancy over a period of years. We recommend this product strictly for flotation applications.

Also works very well for thermal insulation if you build a cooler so that you can pour the insulation.

Dave