Why The Cruel Sea is a credible ASW film

Is the black-and-white film The Cruel Sea a reasonable depiction of anti-submarine warfare or mostly fantasy?

It is a reasonably accurate portrayal, helped by a strong source novel and access to recent wartime personnel.

Both the novel and the film are credible within the necessary limits of cinema. The production was close enough to the war to consult or employ many people who had served in the relevant roles. Some performers and extras brought direct naval experience to the scenes. The result is a useful visual introduction to the strain and practice of Atlantic anti-submarine operations, with the usual limits of a dramatization.