Capstan (nautical) facts for kids

A capstan is a powerful machine used on sailing ships and at docks to pull heavy ropes and cables. Imagine a big, strong post that stands upright. It's very similar to a windlass, which does the same job but lies flat. Capstans help sailors and dock workers pull really heavy things, like anchors or other ships, with much less effort.

Capstans work by using a simple idea: they multiply the force you put in. When you wrap a rope around a turning capstan, even a small pull on your end of the rope can create a huge pulling force on the other end. This is because of friction and the way the capstan turns.

Sailors used to power capstans by pushing long wooden bars, called capstan bars, in a circle. This turned the capstan, slowly pulling in the rope. Today, many capstans are powered by motors, making the job even easier and faster.

A model showing what a capstan looks like. The man to the left is 'tailing' the rope, making sure it grips the turning capstan. Each man's lever helps to multiply his force, making it easier to turn the capstan. These levers were removable. The capstan's power was used for tasks like lifting anchors or sails.

How Capstans Work

Capstans are amazing because they help people do very heavy work. They use a simple machine idea called a lever.

Man-Powered Capstans

When sailors used to turn a capstan, they would push long wooden bars. These bars acted like levers. By pushing the bar far from the center of the capstan, they could create a lot of turning power, even if they weren't super strong. This made it possible for a group of sailors to pull incredibly heavy things, like a ship's anchor, which could weigh many tons!

Motor-Powered Capstans

Modern capstans often use electric motors or hydraulic power. Instead of people pushing bars, a motor inside the capstan turns it. This makes the job much faster and requires less human effort. Even with motors, the basic idea is the same: the capstan helps to multiply the pulling force on the rope.

Uses of a Capstan

Capstans have been essential tools for centuries, both on ships and in harbors.

On Ships

• Lifting Anchors: One of the most important jobs for a capstan on a ship is to lift the heavy anchor from the seabed. This is a very hard task that needs a lot of pulling power.
• Hoisting Sails: Capstans can also be used to pull up large sails, especially on older, bigger ships.
• Moving Cargo: They help lift heavy cargo on and off the ship.
• Mooring: When a ship needs to tie up to a dock, capstans help pull the thick mooring lines tight, securing the ship in place.

In Harbors

• Docking Ships: Capstans on the dockside help pull ships closer to the pier for loading, unloading, or repairs.
• Moving Heavy Loads: They can also be used to move other heavy items around the harbor.

History of Capstans

Capstans have been used for a very long time. Early versions were simple wooden posts. As ships grew bigger and heavier, capstans became more complex and powerful. The invention of steam power and later electric motors changed capstans forever, making them even more efficient.

Sailors often sang special songs called sea shantys while working the capstan. These songs helped them keep a steady rhythm and work together as a team, making the hard work feel a bit easier.

Images for kids

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  This image shows an old-fashioned, man-powered capstan on the side of a ship. The levers that sailors would push to turn it are missing. The strong posts next to it are called bollards, used to hold the rope tight.

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  Here's a man-powered capstan found on a harbor pier. You can see the space around it where sailors would walk in circles, pushing the levers. There's also a gap in the wall for the rope to pass through, connecting to a ship.

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  Even on modern ships like the USS Harry S. Truman, sailors still use motor-driven capstans to pull mooring lines. The capstan pulls the rope, and the bollard posts help hold it securely.

More Images

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  Modern tourists get a chance to turn a capstan. Sailors would sing special sea shantys to help them keep rhythm as they walked around. The capstan could hoist a foresail, lift a heavy spar, or move cargo.

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  Below the capstan, you might find an anchor windlass, another machine used for anchors.

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  This is a diagram from 1883 showing a steam-powered capstan made by Ruston Proctor.

See also

In Spanish: Cabrestante para niños