Torpedo net

Torpedo nets were a passive naval warship defensive device against torpedoes. Their use was common practice from the 1890s through World War II. Torpedo nets were superseded by the anti-torpedo bulge and torpedo belts.

Origins


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 these 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 40ft spars". Experiments were conducted in 1877, with HMS Thunderer becoming the first operational ship to be fitted with the nets.

Early nets were referred to as the "Bullivant type" after the London-based company that produced them. They were constructed from 6+1/2 in steel hoops linked by smaller hoops to form a mesh, with an approximate weight of one pound per square foot (5 kg/m²). These nets were projected out from the sides of the ship on 40 ft wooden poles. Extensive tests were conducted, with the nets proving capable of stopping the contemporary 14 in torpedo without being damaged. A 16 in torpedo with a 91 lb warhead proved capable of causing limited damage to the net.

A heavier net was introduced in 1894 consisting of 2+1/2 in hoops with a weight of five pounds per square foot (25 kg/m²).

Torpedo net cutter
The adoption of these nets resulted in the introduction of the torpedo net cutter on the nose of torpedoes, either in the form of scissors in Japanese designs, or a French pistol-powered version.

Later heavier, denser nets used by the German and British navies were regarded as "torpedo-proof".

Design and use
In addition to new tactical measures (e.g., greater harbor security and rotation of moored vessels out to sea), beginning in 1904 major navies sought a device for protection against torpedo boat attack.

Torpedo nets were the favoured solution. These were heavy steel mesh nets that could be hung out from the defending ship, when moored or otherwise stationary in the water, on multiple horizontal steel 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 were 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.

Russo-Japanese War 1904-1905
In spite of fitting the major ships with anti-torpedo nets, and close danger of war, the Russians did not deploy the nets during the Japanese destroyer torpedo attack on the Imperial Russian Navy stationed on a roadside of Port Arthur on 8 February 1904, which was the opening shots of the Russo-Japanese War.

During other actions later in the war nets were used effectively by the battleship Sevastopol. At the end of the siege of Port Arthur, that vessel was anchored outside the harbor in a position where she was sheltered from the fire of the Japanese batteries but became exposed to persistent attacks from torpedo boats. From 11 to 16 December 1904, Sevastopol was exposed to numerous night attacks. The Japanese employed no fewer than 30 torpedo-boats, of which two were lost, and it was estimated that altogether 104 torpedoes were fired against the ship. One torpedo exploded in the nets near the bow and produced a leak in the torpedo room; another damaged the compartment forward of the collision bulkhead, because the nets yielded to such an extent that the explosion took place near the hull. The last two torpedoes that struck the ship were fired at close range against the unprotected stern: they damaged the rudder and produced a serious leak under the quarterdeck, so that the aft end of the ship sank until it touched the bottom. The leak was repaired. The ship again floated and on the last day of the siege she was taken out to deep water and sunk.

Decline
The sinking by torpedo of three Allied battleships during the 1915 Dardanelles Campaign, all with torpedo nets deployed, demonstrated that the increased speed of newer torpedoes and the tactic of firing several torpedoes at the same location on the target had made the torpedo net ineffective.

Torpedo nets were superseded by the anti-torpedo bulge and torpedo belts.

However, torpedo nets continued in use during World War II to protect ships at anchor, especially as obstacles against submarines, human torpedoes, and frogmen. They were also used to protect dams, and led to the development of bouncing bombs to defeat them, as in Operation Chastise.