By the time the Tribal class enters construction, the Royal Navy would have several years of destroyer experience with the 850 psi plant. A three-boiler arrangement might push output far beyond the historical 44,000 shaft horsepower, although the estimate stops short of applying the full capital-ship efficiency figure at destroyer scale. A two-boiler, two-shaft layout could still provide more power while separating the machinery so one hit is less likely to disable both boilers or turbines. Weight saved by the compact plant could instead support extra torpedoes or 40 mm anti-aircraft weapons, making survivability and combat load alternatives to maximum speed.
Notable Point · 1:05:33-1:08:32
The Tribal class can trade power for survivability
The Tribal-class design could pursue extreme shaft power or use a separated two-boiler plant that still improves performance while reducing single-hit vulnerability.