Mid-ocean refuelling significantly increased the range of warships, allowing escorts like the small corvettes to accompany convoys all the way across the Atlantic.

A tanker (centre) would trail a heavy rubber hose in the water behind it, which would then be picked up by the ship needing to refuel (left). Many convoy escorts, like corvettes, had been designed for operations close to shore. Before mid-ocean refuelling became widespread, they were unable to accompany convoys all the way across the Atlantic; instead, they had to hand off the convoy to other escorts and then refuel in locations like St. John's, Newfoundland, and Iceland.

Fueling Mid Atlantic
Painted by Tom Wood in 1945
Beaverbrook Collection of War Art
CWM 19710261-4869