Hedgehog (weapon)

Hedgehog
On HMS Westcott, November 1945
Type	Anti-submarine mortar
Place of origin	United Kingdom
Service history
In service	1942 to ?
Used by	Royal Navy United States Navy United States Coast Guard Royal Canadian Navy
Production history
Designer	Directorate of Miscellaneous Weapons Development
Designed	1941[1]
Specifications
Shell	65 lb (29 kg)[1]
Calibre	7 in (178 mm)[1]
Barrels	24[1]
Effective firing range	656–850 ft (200–259 m)
Filling	30 lb (14 kg) TNT or 35 lb (16 kg) Torpex[1]
Detonation mechanism	Contact

The Hedgehog (also known as an Anti-Submarine Projector) was a forward-throwing anti-submarine weapon that was used primarily during the Second World War. The device, which was developed by the Royal Navy, fired up to 24 spigot mortars ahead of a ship when attacking a U-boat.^[2] It was deployed on convoy escort warships such as destroyers and corvettes to supplement the depth charges.

As the mortar projectiles employed contact fuzes rather than time or bathymetric (depth) fuzes, detonation occurred directly against a hard surface such as the hull of a submarine making it more deadly than depth charges, which relied on damage caused by hydrostatic shockwaves. During World War II out of 5,174 British depth charge attacks there were 85.5 kills, a ratio of 60.5 to 1. In comparison, the Hedgehog made 268 attacks for 47 kills, a ratio of 5.7 to 1.^[3]