How many Atlantic crossings could a merchant ship complete during the Second World War?
Short answerA ship might manage about six round trips per year, with each full cycle taking roughly sixty days after port and convoy delays.
NotesA merchant ship could make a return Atlantic cycle in roughly sixty days. The ocean passage itself might take about two weeks each way at convoy speed, but sailing time was only part of the schedule. Ships also waited for convoy assembly, moved in coastal convoys, and spent time loading and unloading cargo. Those delays reduced a vessel's annual throughput even when it survived every crossing. Turnaround time is therefore a practical measure of how much shipping capacity the war economy actually possessed.