What is a Capstan on a Ship?

A ship is a giant structure which needs big ropes and strong cables to tame her when at sea. These ropes are of various types with some thicker than the diameter of your arm. Moreover, the ship also uses massive anchor chains that are attached to the ship's anchor.

The process of handling these cables and ropes on board a ship has been a cumbersome task since they were first used. Even though the sizes of ships during the days of wooden sail ships were not as big as those present today, handing the ship’s anchors and sails have always been a tough task. To handle this difficult task a device known as capstan is used. Capstan is one of the simplest yet important devices on the ship. Gradually, the mechanical capstan gave way to the currently used device known as windlass in big ships and electrical capstans for the smaller boats.

In this article we will learn about the evolution of the primitive capstan into the modern day windlass and electric capstans. We will also find out how capstans and capstan winch are useful in ship handling operations.

A ship’s capstan is a drum shaped device that is used for hoisting weights or for winding ship’s anchor cable. A capstan is similar to a windlass, but unlike windlass, it rotates in a horizontal plane and around a vertical axis.

The term capstan was generally used in the days of wooden ships, when the ships were smaller in size. Capstans were used to weigh the ship’s anchors using anchor cables or for hoisting the sails. However, as the size of the ships went on increasing, the size of the anchor cable also became longer. Instead of anchor cables, messenger cables were then used to wound it around the capstan in a continuous loop. The messenger cables were attached to the anchor cables using small lines known as nippers. When the cables were not in use, the nippers were removed to let the cables enter the holds. All these capstans were manually operated by means of wooden bars, attached to slots made in the upper portion of the capstan. The drum was rotated by means of pushing these wooden bars in a clock wise direction.

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As time passed, capstans were completely made from iron and steel. Gears were used at the head of the capstan to provide a mechanical advantage when the bars were pushed anti-clockwise. Even though things improved, capstans still used to be driven by human power, making their usage stressing and difficult.

However, in the modern ships, the traditional capstans are replaced by hydraulically or pneumatically operated windlass. A windlass is a complex device meant for the same purpose as that of capstan, but comprised of different parts, which together make the anchorage process smoother and easier. A capstan differs from a windlass only in the matter of the axis on which the rope or cable is wound (for a capstan it’s vertical axis, whereas for a windlass it’s horizontal)

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http://www.stvincent.ac.uk/Heritage/Warrior/maindeck.html

http://nautarch.tamu.edu/model/report2/index.htm

http://www.tallshiprose.org/info/tour/quicktour/capstan.html

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