The Island also served as a control centre for anti-submarine defences. A degaussing range was established near Murray’s Bay Harbour in June 1941. Degaussing was essentially a counter- measure to magnetic mines laid by Germans, and involved circling each ship with a cable that could carry electromagnetic currents which would neutralise the ship’s magnetism. Ships cabled this way would then be tested against electrified undersea cables. Four loops of cabling were laid at this time including those to Melkbostrand and Clifton.
Reportedly the naval teams who operated these ranges dealt with 4 451 ships during the war. The building complex currently known as Logistics, housed both the listening station and the barracks for the South African Auxiliary Army Service (SWANs) who operated the anti-submarine defences.
Coastal and anti-aircraft gunners were trained on the Island with the 9”2 and 6” batteries, these batteries however were never used against enemy craft. Many of the people trained on the Island served in North Africa. The training of black men and women on the Island was done out of public view and covertly because the official position at the time was that black men should not be armed. Conversely, many of the men in the Cape Corps were black and were unofficially trained to perform rear duties, including guarding prisoners of war. About 2000 Cape Corps men were trained in gunnery. Over 400 women were trained at the artillery school on the Island and a number of these women served in its batteries and operated the various detection systems.