Collided and Sank 9 July 1928
H 47 was a British H Class submarine of 410 tons displacement launched in 1919 and lost following a collision with L 12 in July 1929. She was armed with one machine-gun and four 21-inch bow torpedo tubes and carried a complement of 22. Two sets of Vickers Diesel engines provided a top speed of 13 knots surfaced and 10.5 knots submerged.
9 July 1929 - Sank off Pembrokeshire Coast following collision with HMS L12
On Tuesday 9th July 1929 HMS L12 was at sea with an Officer Training Class; at the same time H47 was on independent exercises in the Irish Sea. At 0800 both submarines were off the Pembrokeshire coast with L12 ahead of H47. L12 suddenly altered course to starboard. H47 at once went full astern and to collision stations. The two submarines crashed together with L21’s bow penetrating about 2 feet. In only 15 seconds H47 began to sink. L12 also began to take in water but her crew managed to control the flood.
