Confirmed. Fleets sailing in convoy and in formation, also sailing in a predetermined pattern (zig zagging for example) can’t stop or they will disrupt the entire fleet. Think of it like stopping a single car in the middle of a busy highway.

More importantly though, a ship that stops to pick up survivors, is a sitting duck for submarines. This was the main reason for the no stopping orders. It would endanger the ship and the entire crew to stop to pick up men fallen overboard. Fear of submarine attack was also the reason for the above stated precautions of convoy, formations, zig zagging, etc.

In most fleets, however, there were specially designated ships that were assigned to pick up survivors of ships sunk in the convoy, usually fast and nimble destroyers. Spotting and picking up a lone sailor would have been next to impossible though. Their job was to stop and pick up mass amounts of survivors from a ship that had been hit and sunk. So yes that man would have watched the whole fleet sail by knowing he was screwed.

In the British merchant convoys in the Atlantic during WW2, for example, they would at times not even be able to stop to pick up whole crews that had survived a sinking, mostly due to lack to escort vessels that were sorely needed to follow and protect the convoy and couldn’t be spared to pick up survivors.