TOPIC: Need foam experts

Well, I cut open my bench seats on my Span/Sea King to find lots of soggy plywood and foam. I've done some research on types of foam and basic uses with costs. It all sounds expensive and great, but do I really need it? Is it for strength or flotation? Some guys are just using the closed cell foam sheets from home depot because the density is almost identical and serves no structual purpose. If the pour in foam is truly neccessary, then I'd like to know the best place to get it. US composites seems to be the place so far.

Erik
No doubt you will receive mixed responses (pun intended)
The coast guard did implement a requirement for flotation foam by manufactures. Is it necessary? I suppose if my boat was sinking and the foam had kept it from doing so....
"little boats sink faster than big ones"
Finally, foam installed correctly, can be a "structural element"
The sub-floor of my predictor was built that way: a single center stringer encapsulated with foam. Aside from the obvious floatation, the foam eliminated the need for any additional stringers or laterals to hold up the floor. If I can ever afford it, I'll replace it.

lar

Well, there are no stringers in the boat technically. I'm thinking about just using the cheapest (2 lb) foam and going for it then. I'd rather not spend the money, and I really don't see any structural value to it... I have to rebuild the seat because of all the wet plywood in there and that seems stronger than the foam. Maybe I can pull off a home depot/ pourable foam kind of hybrid?

I had the bow cushion replaced on the sport fisher and chose the sealed cell foam. One day when I picked it up to drain it the weight ripped open the seams. The old foam was always soaked with water even a week after rain. Moldy...algee...like sitting on a soured dish sponge...never got used. Sealed cell foam is well worth the little extra money, less maintenance is nice and no soggy buns...priceless.

For filling voids with a rigid structural foam, this stuff works great. Smoth-on

Good Luck
CAT*FINk

I went through a bunch of research on this my self. In a nut shell here is the low down on flotation foam. 50% of people say use it 50% of people say don’t use it. The lower lb foams are best for flotation & higher for structural strength. All foams will add some level of structural strength. I don’t want my boat to sink! So I used it. Us composites has the best pricing I found on pourable closed cell urethane foam. It works great. Home depot stuff is for houses not boats, it will soak up water. I hate to say It, but we have the same boat & it sounds like your core/floor is probably mush! Take a 1-1/2” paddle bid & drill just deep enough to remove the fiberglass to inspect a few areas. See what you have going on before you make new seats. Search my archived 2009 posts & check out the pictures. Sounds like the same deal I had going on!

For your seat cavities, how much foam did you use? Also, the foam wasn't poured all the way from one side to the other. I'd assume that it wasn't there for structural purposes. I'm going to do a little investigating with my air cutter and see if the core is water logged as well. I'm hoping to get lucky and maybe find that the core is wet only just behind the seat and then I can address that. I'll try to get some pics taken, because pictures are cooler than words anyway. I'm not too beaten up over it right now anyway. My 1965 Chrysler Sea King 50 has a carb that needs just gaskets and a very clean bowl. The fuel pump needs a new diaphram and some cleaning. So I'm at $125 total into the project.

I bought two of there 16lb kits in 2lb density foam. I did under the front support (what ever you call that) & both seats. I still have about 8lbs left over I think. The expansion of the foam has a lot to do with air temp. Temps above I think 72 = more expansion & below = less. You may be able to get away with one 16lb kit. It will be cutting it really close. I don’t think the foam was originally used with structural strength in mind. But then again, I really don’t know. It does offer a large amount of structural strength by filling a void with a solid mass. I filled my seat cavity’s with the tops off. I have yet to fiberglass the seat tops down. When I do, I will drill a few holes in the seat tops to pour some more foam in to finish the job. Then plug those holes with wooden dowel or plugs of some sort. See what is going on with the floor & take it from there.

I'll probably go with one 16lb kit. I think that I will buy 3/4" plywood and rebuild the seats with that. I'll probably also build some cross bracing inside the seat. I think that would be stronger and will not use as much foam. Hey, plywood floats too! Was the 16lb kit enough for both seats or just one?

I am replacing foam and wet plywood on my Aqua Ray this spring. There should be a thread in 2009 where I asked about this. My decision was to go with 4# foam. The best deal I saw for what I was looking for is Jamestown Distributors.