programme which resulted in two 1120-ton submarines, Explorer and Excalibur, being constructed at Barrow. Built for speed trials only, they were purely experimental, unarmed submarines. Their high-test hydrogen peroxide engines were basically steam turbines, with steam being supplied from the heat generated by the interaction of high-test hydrogen peroxide (HTP), a catalyst and diesel oil.
HMS Explorer had so many teething troubles that her first captain never took her to sea. However, when she eventually made an appearance, in 1958, she was impressively fast, achieving submerged speeds of 25 knots. Her retractable superstructure fittings aided the streamlined hull form.
Provisionally accepted from Vickers in March 1958, HMS
