Sealed Cargo

Sealed Cargo is a 1951 war film about a fisherman, played by Dana Andrews, who gets tangled up with Nazis and their Uboats. It was based on the novel The Gaunt Woman by Edmund Gilligan.

Sailing at night in heavy fog, they hear gunfire. They search for survivors and come upon the damaged Den Magre Kvinde Danish for The Gaunt Woman, a Danish square rigged sailing ship. She appears to have been damaged in a storm and then shelled. Aboard, they discover only the dazed Captain Skalder and a dead body. He claims that his crew abandoned ship in a storm, and that he was subsequently attacked by a Uboat. The Daniel Webster tows the stricken Kvinde to Trabo.Konrad is suspicious he notes that the German gunfire hit above the waterline rather than below it, where a gunner intending to sink a ship would aim, and that while the tarpaulin covering the ships boat is riddled with bullet holes, the boat itself is undamaged. Bannon and Konrad separately sneak below decks to search the hold. When they meet, Konrad has a pistol, but he gives it to Bannon to prove where his loyalties lie. They accidentally discover a second, hidden hold containing rack upon rack of torpedoes the ship is a tender, covertly resupplying the Uboat wolfpacks. They watch undetected as Holger enters the hold and uses a radio to signal the Germans. However, before the pair can alert the military, Skalders crew arrives in boats, so they pretend they know nothing. Skalder plans to resupply the Uboats at Trabo. ........

Source: Wikipedia