SOUTH! THE STORY OF SHACKLETON’S LAST EXPEDITION 1914–1917
"With the exception of the night-watchman we turned in at 11 p.m., and at 3 a.m. on December 23 all hands were roused for the purpose of sledging the two boats, the James Caird and the Dudley Docker, over the dangerously cracked portion to the first of the young floes, whilst the surface still held its night crust. A thick sea-fog came up from the west, so we started off finally at 4.30 a.m., after a drink of hot coffee.
Practically all hands had to be harnessed to each boat in succession, and by dint of much careful manipulation and tortuous courses amongst the broken ice we got both safely over the danger-zone."