Britain had to cover every convoy, while the German surface fleet could choose its moment to sortie. That asymmetry explains the need for several British ships to keep one effective counterforce ready whenever it was required. Readiness included working up crews and maintaining machinery before a convoy sailed. Merchant ships on steady routes resemble buses: their regular speeds and loads make wear comparatively predictable. Warships resemble police cars, alternating quiet periods with sudden maximum effort and repeated high-speed maneuvers. Preventive maintenance therefore had to allow for hard use that a routine mileage schedule could underestimate.
Notable Point · 27:23-30:01
Why one German sortie tied down several British warships
Because Germany could choose when to sortie, Britain needed several maintained and worked-up ships to guarantee that one effective counterforce was always ready.