Torpedo nets

Torpedo nets were a passive ship defensive device against torpedoes. They were in common use from the 1890s until the Second World War. They were superseded by the anti-torpedo bulge and torpedo belts.

With the introduction of the Whitehead torpedo in 1873, and the subsequent development of the torpedo boat, new means were sought to protect capital ships against underwater attacks. In 1876 the British Admiralty Torpedo Committee came up with a number of recommendations for combating torpedoes, which included "... nets of galvanised iron hung around each battleship from projecting 40 ft spars". Experiments were conducted in 1877, with HMS Thunderer becoming the first operational ship to be fitted with the nets.

Torpedo nets could be hung out from the defending ship, when moored or otherwise stationary in the water, on multiple horizontal booms. Each boom was fixed to the ship at one end at or below the edge of the main deck, by a steel pin that permitted the boom to be swung against the ship and secured when the ship sailed. A series of such booms was so fixed at intervals along each side of the ship. When the ship was moored, the free ends of the booms could be swung out with the net hung on the outer ends, thus suspending the net at a distance from the ship equal to the length of the boom, all around the ship. With the net mounted, a torpedo aimed at the ship would hit the mesh net and explode at a sufficient distance from the hull to prevent serious damage to the ship.

Early booms were made of wood, originally 10 inches (250 mm) in diameter but increased in the 1880s to 12 inches (300 mm). Each boom weighed 20 to 24 long cwt (1,000 to 1,200 kg) and cost £28 to £30. In the House of Commons on 9 April 1888 Admiral Field, who was MP for Eastbourne, asserted that steel booms designed by William Bullivant were at least 5 long cwt (250 kg) lighter, one-third less expensive and "superior in many other respects", and asked Lord George Hamilton, First Lord of the Admiralty whether the Committee on Torpedo Net Defence had recommended steel booms and whether the Admiralty would further test them. In reply the First Sea Lord claimed that steel booms doubled up on impact, were more vulnerable to accidental damage and were harder to repair aboard a ship, whereas wooden ones were easier to replace. His Lordship further stated that the steel booms that the Committee favoured were of a different type to those designed by Bullivant.

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