Originally an Admiralty facility, the range became the Royal Naval Torpedo Testing Station and Range, referred to variously as the Loch Long Torpedo Range and the Arrochar Torpedo Range.

Test firing was carried out from submarines, or from a modified vessel, similar to a Clyde Puffer, equipped with two underwater torpedo tubes fitted beneath the bow. This vessel is said have been built in Germany, and been taken from there either during, or after, World War II.

When not in use, this vessel was moored off the Gamble Steps in Gourock, near to the present day ferry terminal and pier. Torpedoes under test were constructed without warheads, and designed to float to the surface on completion of their test run.

Recovery is said to have been by an ex-RAF rescue craft, the Fulmar, which had a low freeboard (the distance from the waterline to the upper deck level, measured at the lowest point where water can enter) which made the operation easier.