Ace Hardware, if you have white hulls go with a product called PC-11. It is an epoxy. Easy to work with. Dries white and is tough as heck. I have been using PC-11 and PC-7(grey) for years.

If you beach your cat alot like I have all my life, epoxy is the way to go. It is tough to sand, but that is a good thing when you are on a beach all the time.