Welman submarine The Welman submarine was a Second World War one - man British midget submarine developed by the Special Operations Executive . It only saw action once and was not particularly successful . Design . Designed by the Commanding Officer of SOE ' s Inter Services Research Bureau ( ISRB ) , Lt Col . John Dolphin as a method of delivering a large explosive charge below an enemy ship , the Welman was a submersible craft in length ( including explosive charge ) , weighing about . Unlike the " Chariot " human torpedo , the operator was enclosed within the craft , and did not need to wear diving gear . The Welman could transport a time - fuzed explosive charge of Torpex , which was intended to be magnetically attached to a target ' s hull . Vision was through armoured glass segments in the small conning tower , and no periscope was fitted . Production . Following trials in the Queen Mary Reservoir near Staines towards the end of 1942 , the Welman was put into production , the production being contracted out to Morris Motors LImited ' s requisitioned factory at Oxford . Despite the craft ' s inability to cut a way through anti - submarine nets ( which both X class submarine s and Chariot manned torpedo es could do ) and the poor visibility available to the crewman , 150 production examples were ordered in February 1943 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 ) . Operational service . In early 1943 the Royal Navy establishment on board the submarine depot ship HMS " Titania " was expanded to carry out sea trials of the Welman . Training courses for operators were located at Fort Blockhouse in Plymouth . Trainees were drawn from the Royal Navy , the Royal Navy Reserve , and other Special Forces groups which included the Special Boat Section of the Commandos . 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 . A Welman ( W10 ) was lost on exercise in Rothesay Bay on 9 September . By autumn 1943 , sufficient trained operators and craft existed for the Welman to be considered for operational use . 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 Boat s ( 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 Sept 1944 by X - 24 ) . On 20 November 1943 MTB635 and MTB625 left Lunna Voe , Shetland , carrying Welmans W45 ( Lt . C . Johnsen , Royal Norwegian Navy ) , W46 ( Lt B . Pedersen , Norwegian Army ) , W47 ( Lt . B . Marris , RNVR ) and W48 ( Lt . J . Holmes , RN ) . The craft were launched at the entrance to the fjord . Pedersen ' s W46 encountered an anti - submarine net and was forced to the surface , where she was spotted by a German patrol craft . Pedersen was captured along with the Welman , surviving the war in a prison camp . The other three , having lost the element of surprise , could not press the attack and so eventually had to be scuttled . Their operators made their way north with the help of Norwegian resistance members and were picked up in February 1944 by MTB653 . The failure made the Royal Navy concentrate on X craft and XE craft , although further Welman trials occurred , especially in Australia . Subsequent to the failed attack the Germans salvaged one of the craft . Even though the German navy were appalled by the unsophisticated quality of the engineering they found in the Welman , there is some similarity between it and the " Biber " midget submarines used against Allied shipping in 1944 . The major drawback of the Welman from its operators ' point of view was that it had no periscope . Without a way of viewing its surroundings without surfacing , it was impossible to navigate covertly . It was also found that when travelling on the surface the operator ' s eye level was so close to sea level that objects more than 2 miles off could not be seen .