Jeff: we have a deck stepped mast on T.P.III
I call the brace between the mast and the
keel,a Sampson post.
It is actually a compression post. A sampson post is traditionally a very strong cleat point on the forward deck that is used for attaching the anchor or mooring rode. Boats designed for towing can also have a samson post on the aft deck. It's nothing to do with the standing rig.