The Jimmy Skiff was designed to be built with epoxy-encapsulated plywood which expands and contracts much less than solid lumber. I would expect that a solid wood bottom would expand and contract at a much higher rate and generate excessive stresses on the structure. Encapsulating the cypress in epoxy wouldn't help because the grain runs in one direction, unlike the multi-directional grain in plywood.

This is only my opinion as I've never tried a cypress bottom on a plywood and fiberglass boat. Cypress is beautiful wood.

Cheers,

Dick