Hank

A fitting or clip used to attach a sail, typically a headsail, to a stay or forestay on a sailing vessel.

A hank is a small, often metal or plastic, clip or hook that is used to secure a sail, particularly a headsail such as a jib or genoa, to the forestay of a sailing vessel. The forestay is the wire or cable that runs from the top of the mast to the bow of the boat, and the hanks are attached to the luff (the leading edge) of the sail at regular intervals. This allows the sail to be hoisted or lowered easily, while keeping it securely fastened to the stay. 

Hanks are typically made from stainless steel or bronze to resist corrosion from the marine environment, though modern versions may also be made from durable plastics. They are designed to open and close quickly, allowing sailors to change sails efficiently depending on wind conditions. The use of hanks ensures that the sail remains aligned with the forestay, which is important for maintaining proper sail shape and performance. 

Hanked sails are common on traditional rigged boats, though modern yachts may use alternative systems like furlers or roller reefing. However, hanks are still favoured by many sailors for their simplicity, reliability, and ease of maintenance.