What ship would be "crushed like an eggshell" if it got caught in the disturbance?
On 21 February 1915, Endurance, still held fast, drifted to her most southerly latitude, 76° 58′S. Thereafter she began moving with the pack in a northerly direction. On 24 February, Shackleton realised that they would be held in the ice throughout the winter, and ordered ship's routine abandoned. The dogs were taken off board and housed in ice-kennels or "dogloos", and the ship's interior was converted to suitable winter quarters for the various groups of men—officers, scientists, engineers, and seamen. A wireless apparatus was rigged, but their location was too remote to receive or transmit signals.Shackleton was aware of the recent example of Wilhelm Filchner's ship, the Deutschland, which had become icebound in the same vicinity three years earlier. After Filchner's attempts to establish a land base at Vahsel Bay failed, his ship Deutschland was trapped on 6 March 1912, about 200 miles (320 km) off the coast of Coats Land. Six months later, at latitude 63° 37', the ship broke free, then sailed to South Georgia apparently none the worse for its ordeal. Shackleton thought that a similar experience might allow Endurance to make a second attempt to reach Vahsel Bay in the following Antarctic spring.In February and March, the rate of drift was very slow. At the end of March Shackleton calculated that the ship had travelled a mere 95 miles (153 km) since 19 January. However, as winter set in the speed of the drift increased, and the condition of the surrounding ice changed. On 14 April, Shackleton recorded the nearby pack "piling and rafting against the masses of ice"—if the ship was caught in this disturbance "she would be crushed like an eggshell". In May, as the sun set for the winter months, the ship was at 75° 23′S, 42° 14′W, still drifting northwards. It would be at least four months before spring brought the chance of an opening of the ice, and there was no certainty that Endurance would break free in time to attempt a return to the Vahsel Bay area. Shackleton now considered the possibility of finding an alternative landing ground on the western shores of the Weddell Sea, if that coast could be reached. "In the meantime", he wrote, "we must wait".
Endurance