A sailboat winch is a mechanical device used to increase leverage when trimming lines (sheets and halyards), consisting of a cylindrical drum, internal gearing, pawls, and a base. Lines wrap around the drum, held by friction, and are tightened by a winch handle, usually featuring self-tailing jaws to automatically secure the line.

Key parts of a sailboat winch include:
Drum: The cylinder around which the line is wrapped. It often features textured surfaces (sandblasted or ribbed) to improve grip.

Base: Fixed to the deck, it feeds the line upward toward the drum and houses the lower bearings.

Winch Handle: A removable lever inserted into the top to provide manual power.

Self-Tailing Jaw: A mechanism on top with a V-shaped groove that grips the line automatically, allowing one person to handle the winch without needing to tail (hold) the rope manually.

Internal Gearing/Pawls: Gears provide mechanical advantage (single or multi-speed), while spring-loaded pawls allow the drum to rotate in only one direction for safety.

Feeder Arm: Guides the line into the self-tailing jaws.

Drum Top/Top Cap: Secures the drum to the central spindle.

Key Materials and Features
Materials: Drums are typically made of anodized aluminum, chrome, stainless steel, or bronze for durability and corrosion resistance.

Power: Usually manual, though many modern boats use electric winches for large sails.