The fastest liners had machinery and hulls designed to maintain more than thirty knots throughout an Atlantic crossing. Warships normally cruised economically and used maximum power for shorter tactical periods, so matching a liner for days imposed very different stresses. Cruisers assigned to such escort work could require months of repairs afterward. Queen Mary, Queen Elizabeth, and later SS United States illustrate the specialized engineering behind sustained transatlantic speed. The operational benefit came with an immense fuel bill, but avoiding a submarine attack justified that cost for troop-carrying liners.
Notable Point · 2:07:47-2:11:12
Why warships struggled to escort the fastest liners
A liner could sustain more than thirty knots across an ocean, while a warship designed to cruise slowly and sprint for battle could damage its machinery trying to match that schedule.