Capstan (nautical)

A capstan is a machine that is used on sailing ships to pull ropes and cables (also called hawsers). It has a vertical axle, and is very much like the windlass, which has a horizontal axle.

Grip on power pull capstan and it's opposite brakeforce on bollard posts; both work thru Capstan Equation

Man powered capstan is a 2nd Class Lever concentrating man force inwards to smaller radius for more power from levers.

Motor powered capstan spins motor shaft from inside post/not outside levers so is a 3rd Class Lever delivering force wider radius than motor shaft force input.

A model showing what a capstan looks like. The man to left is 'tailing' rope with enough friction to grip turning capstan. Each man's lever is concentrating his larger force radius into the smaller capstan post radius for more power. Levers were removable. Output force used for anchor and sail etc.

Ship side old school man powered capstan power pull (missing levers). Bollard posts for brakeforce hold.
Harbor side man powered capstan with levers removed. Given plenty of turning room to crank levers. Also space in wall to serve pulling rope out to ship drawing towards pier.
Navy sailors tailing motor driven capstan still used on US Nimitz 2005. Once again capstan for power pull, and contrasting bollard post for anti-pull of brakeforce.

Capstan (nautical) Media

Tourists turn a capstan. The tensioned portion of the rope would fasten the ship to the quay, hoist a foresail, lift a spar into position on the mast or to transfer cargo to or from a dock or lighter.
Diagram of Ruston Proctor Steam Capstan 1883
Hydraulic capstan left after dockland redevelopment in London
Capstan in Belfast, Northern Ireland
Capstan on the USS Cairo

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