Add foam to a kayak

I was thinking of adding some foam to my old kayak and wanted to know if you all would suggest spray foam so it would stick to the kayak and then expand?

Are you sure?
most non commercial “foam in a can” is open celled and absorbs water like a sponge.If you swamp your cockpit at best, the boat will weigh a lot more and stay swamped, at worst you might sink the boat. I am not sure what any chemical reaction may be with the surface material of the boat either.

If you are looking for additional flotation, bags are available for most every kayak made at a reasonable price. If you are looking to repair the hull there are ways to repair cracks and thin spots that are explained in other posts on this forum.

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Don’t do it!
Aside from the concerns about waterproofness of the foam, there are lots of horror stories of boats that have been split open by the pressure of the expanding foam. The fact that one end of the cavity is open will not prevent pressure issues.

The minimally expanding foams that wouldn’t damage your boat aren’t waterproof. Im sure there is a foam out there that is both waterproof and minimally expanding, but I don’t know if they are available or affordable. It would seem that some of the spray foams that are used a moisture barriers and light insulation for homes would work, but I don’t know about the reactivity if it. Plus they are more of a commercial product with limited availablity to consumers. I would just stick with float bags.

Ryan L.

Are you
wanting to add a bulkhead? I used a piece of closed cell foam, cut it to size and pressed it in place. Works great. If you’re not adding a bulkhead, I agree with just adding float bags.

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It can be done with pourable foam
I bought a WW boat the had the nose poured full of foam instead of footpegs. I’m not sure if it has different composition than the spray foam.

If you have a way to secure the foam you could line the space with a non reactive plastic then fill the plastic with foam making it removable. Something as simple as a couple cords embedded in the foam and going to a deck fitting could work to secure it.

Good Luck


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Randy, stand the kayak on end and
pour water over that foam. Chances are, you’ll feel the bow heavier after you pour the remainder out. I do not know of any foam that expands substantially when sprayed in a boat, but doesn’t soak up water. If one wants flotation in front of the bulkhead, one uses shaped minicell or a properly chosen float bag.

Yer need a "Gray Thing"
Contact P-140 fer details.


Why would you want to remove it?