HMS H42

HMS H42 was a British H class submarine built by Armstrong Whitworth at Newcastle upon Tyne, laid down in September 1917 and commissioned on 1 May 1919. On 23 March 1922, while practising torpedo attacks against destroyers off Europa Point, Gibraltar, she surfaced unexpectedly ahead of the destroyer HMS Versatile, which rammed her abaft the conning tower and almost sliced her in half; all 24 of her crew were lost, and an investigation found H42 at fault for surfacing where she did against instructions. She displaced 423 long tons on the surface and 510 long tons submerged, was 171 feet long, carried four 21 inch bow torpedo tubes and eight torpedoes, and was a Holland 602 type boat designed to Royal Navy specifications.