I've used these for years. I buy the hollow ones, string a piece of bungee thru them and tie them around the hulls both forward and aft. I usually use two or three sections, each with a bungee through it, and then I tie the two or three sections together with the bungees so they are spread out along the bottom. They really work great and hold up to weathering too. After a while, they will take a "set" and stay a bit flat, but, hey, for less than $10 they work great. I've also used the smaller ones as hiking strap covers to ease the stress on my legs.
Try it, you'll love them!
Jon Hamlet
Taipan #217