: As Im painting the kayak I am currently building I was thinking of using some
: kind of easily sandable filler instead of just filling the cloth with
: ordinary epoxy. Sort of what I see when watching the guys in American
: Hotrod (Discovery channel) fairing the body of a car.

I paint my VOLKSKAYAKs, and made the mistake of using auto body filler and spot and glaze putty when finishing the fairing of my first boat. Reckoned it'd be far, far quicker, which it was (several coats applied and sanded out each day, vs. a day or two to cure between coats!), and I did get an extremely smooth job...but for a very short while.

Then the trouble started - blisters beneath the paint and the fairing compound - big blotches and patches all over the bottom - I've been digging out bad compound and refairing with microbaloon-thickened epoxy every spring since 2003. My second VK, done in 2003, was faired with microbalooned epoxy - no problems at all so far. Others may have had better results using polyester-based compounds, but I'm saving them for the aged and rusting 4Runner in the future...