Boom (navigational barrier)

A boom is a special kind of barrier placed across a stretch of water to control or block ships and boats from passing through. Sometimes called a chain, these barriers can be made from many different materials and are often mixed with things like pile barrages to make them stronger.

Today, booms are mostly used for safety reasons, like stopping people from entering dangerous parts of a river. But in the past, they were often used in wars to stop enemy ships from reaching a certain area. For example, a modern boom can act like an anti-submarine net to protect important places.

Besides safety and war, booms have also been used to make ships stop and pay a toll before they could continue their journey. This helped people in charge of the area collect money from passing vessels.

Description

A boom is something that floats on the water's surface to block or control movement. Sometimes, a chain is used instead, and it can be placed either on the surface or below the water. This chain can be made to float by using rafts, logs, ships, or other wooden materials, turning it into a boom as well.

Historical uses

In medieval times, a chain or boom could be attached to a special chain tower or boom tower. This made it easy to lift or lower the chain safely because these towers were strong and protected. By lifting or lowering the chain, people could decide who was allowed to pass through the water.

Sometimes, big ships could break through these chains, like during the siege of Damietta, the raid on the Medway, and the Battle of Vigo Bay. More often, attackers would capture the towers and cut the chains using regular tools. For example, during the siege of Derry, sailors in a small boat cut the boom there.

Because these booms were important for protection, they were often guarded by soldiers. This could include towers on land, artillery positions, or forts. In the Age of Sail, ships with big cannons could also help protect the boom by firing their broadsides at anyone trying to break through. Sometimes, several booms would be placed across the same stretch of water for extra safety.

Examples

Historical

• The entrance to the Cothon at Carthage had a chain for protection.
• A chain guarded Portsmouth Harbour from 1431 to 1539 at Fort Blockhouse.
• The Leonine Wall used a chain to block the Tiber.
• A chain stretched across the Golden Horn.
• A chain and boom stopped ships on the River Medway during the Raid on the Medway.
• The Hudson River Chain was used as a barrier.
• The Parana River had a chain during the Battle of Vuelta de Obligado.
• During the American Civil War, a chain was put across the Mississippi River from Columbus, Kentucky to Missouri to stop Union ships.
• A chain was placed between the A Palma Castle in Mugardos and Saint Philip Castle in the ria of Ferrol to protect the city and naval base.