Type B Depth Charge (UK)
The British Type B Depth Charge was an early, small antisubmarine weapon adapted from the "Vernon boom" described in the Annual Report of the Torpedo School, 1915.
The Type B was similar to the Type A Depth Charge, but by discarding the heavy outer chassis float in the original model in favour of a "fisherman's float", 40 pounds (19%) were saved from the overall weight. As it had the same 32.5 pounds of gun cotton initiated by a G.C. primer of 2.25 pounds, this gave the Type B an explosive weight of 1⁄5th the overall weight – not great but a big improvement. Vernon calculated that this gave the weapon a 10 foot danger radius.
As in the Type A, explosion was triggered mechanically by a float and wire system. The single depth setting of 40 feet used in the Type A was augmented by an 80 foot setting which could be selected by withdrawing a pin before dropping the charge. The Type B was in general use by small craft in October 1915.
The final refinement on the Vernon boom-derived depth charges would be the Type E, which greatly increased the proportion of explosive comprising the overall weight.
- Annual Report of the Torpedo School, 1915. Plate 82.
- Annual Report of the Torpedo School, 1915. pp. 164-5, 172, Plate 73, Plate 82.