Wartime speed depends on acceptable engineering risk

Harwich Force movements suggest Ben-my-Chree could sustain about 26 knots and may briefly have reached 27 to 27.5 knots, despite an official naval rating of 24.5 knots. Better coal, machinery tuning, and wartime urgency all offered reasons to push harder than a peacetime trial would allow. The limiting factor was often the risk of hull or machinery damage rather than the last fraction of power available from the turbines. A comparison with rules against firing superfiring turrets shows the same distinction: a navy avoids preventable damage during exercises but accepts more risk when failure to act could lose a battle. The higher reported speed is an operational estimate rather than a revised official specification.