A significant portion appears to have been shot within a large water tank at Ealing Studios using painted scenery, which occasionally betrays the artifice, but there remains a compelling narrative of perseverance and bravery. The oil tanker “San Demetrio” finds itself directly in the path of the 11-inch guns aboard the German battleship “Scheer”. After sustaining severe damage and being exposed to the elements, the crew receives orders to evacuate; however, after two days adrift in the turbulent Atlantic, they unexpectedly encounter their former vessel—and it’s still capable of floating! Under the direction of their second officer (Ralph Michael) and the engineering chief (Walter Fitzgerald), the men determine that remaining on board offers better prospects than facing the sea alone, and so they begin efforts to navigate the ship toward the safety of the Clyde. Produced during wartime, there's inevitably a propagandistic aspect to this account of actual events, but it doesn’t diminish the suspense that director Charles Frend generates, nor does it lessen the quality of the performances from a group of familiar British actors who were tasked with reassuring audiences in the UK that the nation would continue fighting and succeeding against seemingly insurmountable challenges. It's a story illustrating how hazardous these convoy voyages were to undertake and safeguard, and the black-and-white cinematography effectively communicates a feeling of coldness, dampness, darkness, and peril as inexperienced sailors attempted to contend with both human adversaries and the harsh forces of nature.

Source on TMDB