The Sidon was scuttled at the current location in 1957 to be an SDIC (Anti-Submarine Detection Investigation Committee) target. However, that is only a minor part of her history. She was commissioned in Nov 1944, on the eve of World War II, patrolling initially the European waters and in July 1945 (after VE day in May) she left for the Far East. She returned in 1946 and was part of the post war Royal Navy.
In 1955, she was fitted out with some experimentally MK12 torpedoes - converted MK8 torpedoes using HTP (High Test Peroxide) motor (an idea copied from captured German torpedoes in World War II). Unfortunately, the material in the MK12 reacted violently with HTP and exploded while it was in the torpedo tube, blowing open both end of the tube, flooding the submarine and sinking her in Portland Harbour. 12 crew members died plus a surgeon who was part of the rescue party.
She was raised and moved to nearby causeway, where the bodies removed and buried in a nearby naval cemetery. Two years later, in 1957, she was pulled free and moved to her current location and is used as a sonar testing target.
For a very detailed history of her life, visit the dedicated website by clicking the button below:
HMS Sidon - Deep Quest