The first case study is the French Dupuy de Lôme class, laid down in 1913 as an attempt to give a submarine fleet-relevant surface speed. The design had a 2,350-nautical-mile surface range at 10 knots, a 120-nautical-mile submerged range at 5 knots, triple-expansion steam engines, and an 18-knot maximum on the surface. Its 10.9-knot submerged speed was notably high for 1913-14, while eight 450-millimetre torpedo positions, a 75-millimetre gun, and a 47-millimetre Hotchkiss gun gave it substantial armament. The difference between its 853-ton surface displacement and 1,291-ton submerged displacement also reveals the large amount of water needed to dive. The comparison with the earlier Dupuy de Lôme armoured cruiser places the submarine within the evolution of French Jeune École ideas about torpedo attack and commerce raiding.
Notable Point · 0:54-5:28
The Dupuy de Lôme-class steam-submarine experiment
The Dupuy de Lôme class shows why French designers tried steam machinery, high surface speed, and heavy armament in a submarine laid down just before the First World War.