The Princess engines suggest another application in Fairmile D coastal craft. Their existing four Packard engines are credited with a total of about 5,000 horsepower and an official full-load speed of 29 knots. The speculative replacement uses compact coupled engines to reach as much as 15,000 horsepower in roughly the same machinery space. A speed in the high thirties is offered as an estimate, rather than a calculated design result. That would narrow the advantage held by German Schnellboote. Sea conditions matter because the British boats are credited with retaining their speed better in rough North Sea water, while the German boats' higher sustained speeds depend on calmer conditions. This machinery advantage would affect several British services, but it would leave Bomber Command's institutional problems unresolved.
Notable Point · 4:35:36-4:40:12
Turbine-powered Fairmile D boats against Schnellboote
Compact coupled turbines could narrow the speed gap between Fairmile D boats and Schnellboote, especially when rough water limits the German advantage.