Squid (weapon)

Development

Ordered directly from the drawing board in 1942, under the auspices of the Directorate of Miscellaneous Weapons Development, this weapon was rushed into service in May 1943 on board HMS Ambuscade. The first production unit was installed on HMS Hadleigh Castle; it went on to be installed on 70 frigates and corvettes during the Second World War. The first successful use was by HMS Loch Killin on 31 July 1944, when she sank U-333. The system was credited with sinking 17 submarines in 50 attacks over the course of the war - a success ratio of 2.9 to 1. In contrast, out of 5,174 British depth charge attacks in WWII there were 85.5 kills, a ratio of 60.5 to 1. The Hedgehog made 268 attacks for 47 kills, a ratio of 5.7 to 1. By 1959, 195 Squid installations had been produced.

This weapon was a three-barrel 12-inch (305 mm) mortar with the mortars mounted in series but off-bore from each other in order to scatter the projectiles. The barrels were mounted in a frame that could be rotated through 90 degrees for loading. The projectiles weighed 390 pounds (177 kg) with a 207-pound (94 kg) minol charge. On some vessels, the Squid installations were at the stern – the bombs were fired over the length of the ship and dropped into the sea slightly ahead of it. Sink rate was 43.5 ft/s (13.3 m/s) and a clockwork time fuze was used to determine the detonation depth. All three projectiles had to be set to the same depth; this could be continuously updated right up to the moment of launch to take into account the movements of the target. The maximum depth was 900 feet (270 m).

The weapons were automatically fired from the sonar range recorder at the proper moment. The pattern formed a triangle about 40 yards (37 m) on a side at a distance of 275 yards (251 m) ahead of the ship. Most Squid installations utilised two sets of mortars. All six bombs were fired in salvo so they formed opposing triangular spreads. The salvos were set to explode 25 feet (7.6 m) above and below the target, the resulting pressure wave crushing the hull of the submarine. Post-war trials found Squid was nine times more effective than conventional depth charges.