JEM Watercraft

I've read that expanded polystyrene can be used as a filler for pontoons but was wondering if polyurethane foam could be used instead?

This is the kind of foam you should be using:

http://uscomposites.com/foam.html

The FAQ link has some very good info.

It seems to me that even with a foam that will not absorb water itself, it will still harbor moisture in between the foam itself, and walls of the pontoon. This condition would only worsen with time.

Another approach is to leave them hollow as constructed, and put on sealable hatches. That way, you could vent and dry the interiors during storage. Could even carry some non-essential gear that you don't need ready access to in there.

Thank you for all the information, it seems that USC is the place I should be going for to get most of my materials.

Matt - Do Jemmer's get any discount at USC?

No, I'm afraid no current deal in place. But perhaps I'll try changing that.

U.S. Composits has lots of good products. Their epoxy is cheap but you have to be careful about amine blush with their medium and fast hardeners. Their mixing ratios can also be a pain.

But I've used it for many projects and the epoxy performs nicely. Nice selection of fiberglass and other toys.

Another approach is to leave them hollow as constructed, and put on seal-able hatches. That way, you could vent and dry the interiors during storage. Could even carry some non-essential gear that you don't need ready access to in there.

I'd say Jack's got the best idea on this one. A permanently sealed void on a wood boat, even epoxy coated, or one filled with a non-removable foam, can be the source of problems that you won't be able to see until it's too late.

With hatches, not only can that space be used for gear storage, but you can also fill it with removable flotation. This can be in the form of flotation bags, store-bought or home-made, or something as simple as sealed plastic jugs.

You can reduce the amount of air in the bags or take out some of the jugs, if you need some extra storage. And you'll never be wondering if anything is going on in there, where you cannot see it.

As for flotation, nothing is more buoyant than air.

Mike S.
Spring Hill, FL

FlaMike wrote:... As for flotation, nothing is more buoyant than air.

Thanks, Mike, for the back up. Helium or hydrogen would be more buoyant, but too much of a PITA for the benefit.

(going back to sleep now)