Keeping twelve destroyers on patrol required a larger force

Pound's scheme would concentrate available Mediterranean destroyers and a Home Fleet division in the western basin. Four groups of three ships would patrol while the rest of the force supported the rotation. Each unit would spend seven days on patrol and nine days at sea in every fourteen. Dockings and refits meant the Home Fleet would ultimately need to provide a whole flotilla to maintain twelve destroyers on patrol. Separate detachments would cover other areas because ships in the western basin could not respond quickly enough to distant incidents.