Originally Posted by JohnRPollard
That is a fairly standard cruising mainsail arrangement.
The "shelf-foot" refers to a sail foot that is connected to the boom along it's full length.
Well, yes, but with extra material that unfolds if the outhaul is eased, thus creating the "shelf." There is also a footed main, which our boat's original main is, which simply has slugs, a bolt-rope or some other attachment mechanism for holding the length of the foot to the boom.