“Very beautiful weather,” Schwieger noted, in a 4:00 A.M. entry in his log. The boat was abreast of Sule Skerry, a small island west of the Orkneys with an 88-foot lighthouse, said to be the most remote and isolated light in the British Isles.Schwieger sailed a southwesterly course. He saw no targets but also no threats and was able to stay on the surface the entire day. Toward nightfall, at 6:50 P.M., he at last spotted a potential target, a steamer of about two thousand tons. It flew a Danish flag off its stern, but Schwieger’s war pilot, Lanz, believed the flag was a ruse, that the ship was in fact a British vessel out of Edinburgh. It was heading toward U-20. Schwieger ordered a fast dive, to periscope depth.Now began the complex choreography that would determine whether he could add this ship to his personal tally of sunk tonnage. Men ran back and forth under the direction of the ship’s chief engineer, to help keep the boat level, as the helmsmen adjusted the horizontal and vertical planes.
