A curve in the foot of a square-sail, by which the clews are brought below the middle of the foot; the forward leach of a fore-and-aft sail.
a clearly defined elevation in the center of the back above a horizontal line drawn lengthwise at the base of the withers such that the spine arches
The curve of the trailing edge of the sail
The curved portion of a sail extending past a straight line drawn between two corners. In a mainsail, the roach extends past the line of the leech between the head and the clew and is often supported by battens.
sail area aft of the leech line. Class rules define roach area for each sailboat class.
The up and outward curve in the leech of the sail.
In a mainsail (or a jib), the sailcloth which extends aft of a straight line between the head and the clew. Generally battens are required to support the roach. [ see photo