A steam plant's design speed assumes that its machinery will survive years of service with regular maintenance. Higher output first shortens the distance between maintenance periods, then consumes machinery life, and can eventually make a major refit or sudden failure an accepted risk. The practical limit also depends on turbine strength, shafts, propellers, cavitation and the resistance of the hull. Samuel B. Roberts at Samar and Rodney during the Bismarck chase illustrate why crews might accept those costs when survival or interception depends on speed. An experienced engineering team has to judge how much more its particular plant can deliver. Fuel exhaustion, boiler failure and damage to the turbines or propellers impose different limits on how long that effort can continue.
Notable Point · 59:25-1:04:38
Emergency speed consumes machinery life
An engineering crew can extract additional speed by accepting shorter maintenance intervals, permanent wear and an increasing risk of machinery failure.