Today’s invention is a way for sailing boats to stow and hoist their sails without all the usual rolling and stowing and yo-ho-hoing.
The sail itself would be a stiff shell, exactly mirroring the hull of the boat.
This would be attached to a curved rail running from fore to aft and which would rotate about the long axis of the vessel. This would allow the sail to be mechanically extracted from the slot in which it is stored.
The rear section of the rail would carry no sail, so that the wind could enter via this gap and help drive the boat.