Sail batten

Catamaran with full-length battens on the mainsail.

On sailboats, a sail batten is a flexible insert in a sail, parallel to the direction of wind flow, that helps shape its qualities as an airfoil.^[1] Battens are long, thin strips of material, historically wooden but today usually fiberglass, vinyl, or carbon fiber, used to support the roach of a sail. They are also used on tall ships to form the ladders up the shrouds in a fashion similar to ratlines.

^ Textor, Ken (1995). The New Book of Sail Trim. Sheridan House, Inc. p. 228. ISBN 0924486813.

[Textor-1] Textor, Ken (1995). The New Book of Sail Trim. Sheridan House, Inc. p. 228. ISBN 0924486813.

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