Why a warship's true maximum speed is elusive

Do we know the true maximum speeds of Royal Navy capital ships and cruisers?

No precise universal figure is offered: official, design, and emergency speeds can differ when machinery is driven beyond its normal limits.

A warship's official speed can differ from the speed it was probably designed to achieve. A further figure may emerge when a captain orders the engineering department to extract everything possible in wartime. The example involves removing stops and opening valves beyond the normal operating limits. The speed reached under those circumstances can differ from the published figure, so the same caution applies to British, American, and modern warships.