Save a Sinking Kayak...

[dgax65]

You can use inflatable hull fenders for flotation. I used to have 8 fenders strung together in two daisy chains. I could slide a string of four outside the scupper posts in the hull of my Drifter. The fenders are extremely durable and hold air virtually forever. The problem with them is the weight and the loss of internal storage space. When I started paddling an X-Factor with a Kayatank I lost the ability to stow rods on the centerline. I had to stow them outboard of the scupper posts. To do that, I had to scrap the fenders. I only kept a couple in the stern and one in the bow; just enough to keep a swamped yak near the surface.

Inflatable fenders
http://www.defender.com/product.jsp?path=-1|10391|321174|30250|321909&id=1110593

As I mentioned in the thread about pool noodles, they won't make a swamped kayak stable enough to hold you upright, but they will keep it at the surface so you can recover your gear and the kayak. I flooded my Drifter just to see how it would handle with 7 fenders inside. It remained floating with the deck barely awash, but I couldn't sit on it.