I use 3" mini cell foam for bulkheads/ flotation. I cut it to shape and silicone it after I position the bulkheads where I want them. It gives me nice water tight compartments, and doesn't really add too much weight.

make sure its closed cell foam , i watched a guy sink his boat using open cell foam

I was thinking of using pourable foam see the link below.  Has anyone used this our is the minicell the way to go.

Thanks

 Nate

http://www.jgreer.com/pour_foam_faq.htm

I've used that stuff, but not for kayaks. I filled the voids in my latest sailing dinghy with it (picture shows the space around the mast box, under the anchor locker). You need to allow lots of room for expansion. It has a lot of power behind it when it puffs up. If you just try to pour it into a space through a single small hole, it'll rupture the compartment. Once it cures, you can cut it with a saw, sand it, use a rasp, etc. It makes a very messy and irritating dust, so use breathing protection. Eye protection is also helpful.

It's closed cell, just like minicell, but not in the least flexible. Once it's cured, it's a structural component. If you were to fill the hatches in a kayak with it, the yak would be unsinkable and you could tap dance on the decks. It'd add 2 lbs per cubic foot to the weight of the kayak.

You need to cover it with some kind of surface to prevent abrasion. In my dinghy I put a sheet of wood on it. A thick layer of glass can also work, depending on the compartment, but wood is usually better.

Laszlo

Is the spray foam insultation you can buy at the local hardware store the same stuff?  How much would you need to keep your kayak afloat on a Chesse 17LT?  Could I create a small bulkhead about 12 inches from each end and fill it with the foam after the end pours?  Will it effect the performance of the kayak?

Anyne suggestions on my question above?

No - that's insulation, not structural foam.

None - The 17LT floats just fine without any foam in it at all. What the foam is good for is to prevent flooding in case of a puncture (or losing your hatch), so you'd want to fill your hatch spaces. Complete fill means no water ever, partial fill means  some water. Each cubic foot of foam provides 6 lbs net buoyancy.

Yes, but may not make enough difference to be worth it.

Yes, each cubic foot will add 2 lbs weight to your kayak.

Hope this helps,

Laszlo

Thanks Laszlo, I think I'll skip the foam.

I think the net bouyancy is closer to 60 pounds per cubic foot, if my math is correct.  A cubic foot = about 7.5 gallons, and each gallon weighs about 8.3 pounds.  So a cubic foot of water would weigh about 62 pounds compared to 2 pounds per cubic foot of foam. 

You are correct, nate. I meant 62 net (64-2), but the keyboard ate my digit. Well spotted,

Laszlo