and Sulzer engines. (Difficulties obtaining the Sulzer engine and the impracticability of a MAN design prevented this.) In November 1914, Vickers were given orders for six more boats, G8 to G13, and to build the engines for four of the class building at Chatham. G14 was ordered from Scotts on the Clyde.
Costing an estimated £125 000, the G Class were twin-shafted vessels, with two eight-cylinder diesels that together generated 1600 bhp, giving a surface speed of 14 knots. Two single armature motors, each of 420 bhp, gave a submerged speed of 9 knots. The class carried 200 cells in two battery tanks, which gave a submerged endurance of 95 miles at 3 knots.
Early war experience gained by other classes led to the proposed
