Shackleton chose five men to go with him. Worsley would navigate. Tom Crean would be the second officer. McNish would be there for his mechanical and carpentry skills, despite the friction between them on the ice. Timothy McCarthy and John Vincent, both able seamen, completed the crew. The choice of McNish was pragmatic: if anything went wrong with the boat during the crossing, he was the only man who could fix it.
Vincent, the physically strongest man on the expedition, would have a hard time of it. On the passage, he was frostbitten from drinking from a metal cup in the wind and lost part of his upper lip to the cold. He was largely incapacitated for much of the voyage and was unable to participate in the overland crossing on South Georgia.
On April 24, 1916, the James Caird departed Elephant Island. The 22 men remaining on the island, under Frank Wild’s command, watched it go. Shackleton had told Wild to move the camp if necessary, to launch one of the remaining boats if it became clear rescue wasn’t coming, and to keep morale together. He had then climbed into the James Caird and sailed away into the Southern Ocean, and the men on the island could only wait.
The crossing took 16 days.
The conditions in the Drake Passage and Scotia Sea in April are, by the standards of oceanography, severe. The Southern Ocean has no land mass to interrupt its circulation, and the wind and wave patterns it generates are among the most powerful on earth. The James Caird was battered continuously. Ice built up on the decking — at one point it reached fifteen inches thick — and the crew chipped it off by hand and threw it overboard to prevent the added weight from swamping the boat.