Designed by Commander S.M. Terry, RN, 21st October 1942 Principal advantages are:

• Streamlined for more speed and economical propulsion.
• Crew sit inside back to back.
• A larger warhead.
• Better controls all contained in the driver’s cockpit.
• Depth gauge, air gauge, clock and compass.
• Guard wire over the cockpit protecting occupant’s head.

Length: 30 ft 6 in (9.3 m)
Diameter: 2 ft 6 in (0.8 m)
Max height: 3ft 3 in (1 m)
Weight: 5,200 lb (2,359 kg) with warhead
Armament: 1,000 lb explosive charge (weight 1,500 lb – 680 kg)
Max speed: 4.5 kt (8 km/h) @ 655 rpm
Range: 5-6 hours at full speed
Depth: 600 ft (183 m)
Operational depth: Limited to 30 ft (9 m)
Number built: 30

Built by Stothert and Pitt (Crane Makers) at Bath.
Painted with a metal primer then covered with olive green Bitumastic manufactured by Wailes Dove Bitumastic Ltd.