I painted my inflatable for years. Started with a quart of inflatable
bottom paint from West Marine... poured out a bit, made a slurry of
Cayenne pepper and water, and added about 1 oz. of pepper to the can
along with a vial of Starbrite's compound X. Mix that up well, then add
as much of the paint you poured off as it will hold and mix again. This
works great! I have left the dink in for a year straight, with nothing
but a little slime and maybe 10 barnacles on it.

The straight dinghy bottom paint isn't worth a flip. The first time I
tried it, I had several hundred barnacles within 8 weeks. Be sure to
add at least the Cayenne pepper.