Well...I like full-batten mains and there seems to be a lot of favorable comment about loose footed mains and the shelf-foot seems to be a more expensive variant on the loose foot:
From Halsey Sails...
|Shelf Foot and Loose Foot |
The Shelf-Foot and Loose-Foot constructions are options that allow us to add a substantial degree of extra fullness in the lower portion of the mainsail in order to improve racing performance on reaches and runs. In very light air, the improved performance is achieved even to windward. The extra fullness is removed by tightening the outhaul. When the outhaul is eased, the sail maintains an airfoil shape down to the boom. With the Shelf-Foot option, a light piece of material connects the sail to the boom. With the outhaul eased, the connecting material unfolds and forms a shelf between the bottom of the main and the boom. When the outhaul is pulled tight, the shelf closes up and lays against the side of the boom.
| || Loose-Foot construction does away with the shelf material. The sail is only attached to the boom at the tack and clew. This attachment method is equally as strong as that of the foot attached to the boom. Many boats are switching to Loose-Footed mains because they make it easier to bend on your mainsail and to remove the sail from the boom — and it's less expensive.|