There is no need to fair the bottom of an unpainted Express 27. In contrast to most other production boats, the E27 mold was faired and the boats came from the factory with fair bottoms!!

A couple of coats of Interprotect barrier coat before the antifouling paint would be a good idea. The type of anti-fouling paint might depend on whether or not you have easy access to a hoist for cleaning the bottom periodically. In any event, get the best anti-foulding bottom paint recommended for salt water. Anti-fouling paint is not a good product for going cheap. I don't know what's best for San Francisco Bay conditions. I've had good luck on a bigger boat in Mexico with Interlux Ultra which claims to be formulated for warm water and troublesome fouling conditions.

Painting the bottom would probably reduce the re-sale value slightly in the Bay area where nearly all the racers dry sail. But we'll take it in Detroit where everybody wet sails!