Type of wood used for spine?

[SkunkBoat]

Not sure what you mean.

There is no wooden keel in a v20. Just glass hull with stringers and bulkheads. There is a piece of plywood glassed into the bilge for mounting a bilge pump and there is some plywood glassed in for backing the bow eye. There is a strip around the hull sides for screwing the cap to the hull and screwing the rub rail.

There can be a pvc pipe glassed in running under the fuel tank.