Many of the original crew also continued to serve on Oceanic. In effect therefore Oceanic had two captains, and this would lead to confusion about the chain of command. WreckingOceanic headed for Scapa Flow in Orkney, Britain's main naval anchorage, with easy access to the North Sea and the Atlantic. From here she proceeded north to Shetland travelling continuously on a standard zigzag course as a precaution against being targeted by U-boats. This difficult manoeuvring required extremely accurate navigation, especially with such a large vessel. In the end it appears to have been poor navigation, rather than enemy action, that was to doom Oceanic. An inaccurate fix of their position was made on the night of 7 September by navigator Lieutenant David Blair RNR (previously assigned to, then reassigned from, the ). While everyone on the bridge thought they were well to the southwest of the Isle of Foula, they were in fact an estimated thirteen to fourteen miles farther north than they believed and to the east of the island instead of the west. This put them directly on course for a reef, the notorious Shaalds of Foula (also known as the Hoevdi Grund and so marked on charts), which poses a major threat to shipping, coming within a few feet of the surface, and in calm weather giving no warning sign whatsoever. Captain Slayter had retired after his night watch, unaware of the situation, with orders to steer to Foula. Commander Smith took over the morning watch. Having previously disagreed with his naval superior about navigating a ship as large as Oceanic in the dangerous waters around the Scottish islands, he instructed the navigator to plot a course west, and out to sea, away (so he thought) from hidden dangers like outlying reefs. Unbeknown to Smith, this put the ship onto a course between the island and the reef just south of it. Slayter must have felt the course change, as he reappeared on the bridge to countermand Smith's order and made what turned out to be a hasty and ill-informed judgement, as the ship again changed course directly towards the reef. The ship ran aground on the Shaalds on the morning of 8 September, approximately 2.5 nautical miles (5 km) east of Foula's southern tip. She was wrecked in a flat calm and clear weather. She was the first Allied passenger ship to be lost in the