Despite the craft's inability to cut a way through anti-submarine nets (which both X class submarines and Chariot manned torpedoes could do) and the poor visibility available to the crewman, 150 production examples were ordered in February 1943.

[2] Production was halted in October 1943 when operational research showed the concept suffered from too many disadvantages, by which time some 100 examples had been produced (precise numbers are unknown).

HMS Titania was relocated to Loch a' Chàirn Bhàin, south of Cape Wrath, in the north west of Scotland, which became a secret training base for all mini submarine operations.

In the autumn of 1943 the Combined Ops commander, General Sir Robert Laycock (who took over from the then Lord Louis Mountbatten) decided that the Welman was unsuitable for their purposes, so the craft were returned to the Royal Navy.

Admiral Sir Lionel Wells, Flag Officer commanding Orkney and Shetland, thought they might be useful for attacks on German shipping using coastal waters inside the Leads off Norway.

Motor Torpedo Boats (MTBs) of the 30th Flotilla, manned by officers and men of the Royal Norwegian Navy, were making these raids already and agreed to try the Welmans in an attack on the Floating Dock in Bergen harbour (eventually sunk in September 1944 by X-24).