stringer question

[Bushwacker]

No need to add foam to the stringer unless you just want some more flotation; the foam provides no structural benefit. The 23's seem to have foam filled stringers, but it's just there for flotation, since the foam doesn't have much load-carrying capability. On the wood encapsulated keelson, most of the load is carried by the glass, so even if the wood rots out, it's no big deal structurally. The stringers in the 20's are hollow, were laid up separately from the hull and then installed about half way thru the lay up of the hull. Check the Boating Magazine article in the Literature section on the 20' Seafari - it contains a very detailed sketch showing how many layers of mat and roving were used in the hull and stringers.