Surface warships could devote more internal volume to a single propulsion plant, while a conventional submarine needed machinery for both surface and submerged travel. Early boats had to carry batteries and electric motors as well as a separate surface-power system inside a dense pressure hull. Seals, ventilation, charging arrangements, and immature engines multiplied the reliability problems. These constraints placed fleet submarines at the edge of contemporary engineering rather than making speed a simple matter of installing more power. Nautilus and Swordfish are introduced as Royal Navy test beds, showing that the service tried intermediate technologies before committing to the K class.
Chapter · 5:54-9:50
Why early submarines struggled to match battle-fleet speed
Dense hulls, dual propulsion systems, battery limits, and immature engines made battle-fleet speed exceptionally difficult for early submarines.