Two pressure waves struck the ship on 29 August without incident. On the evening of 31 August, a slow-building pressure gripped the "Endurance", causing her hull and timbers to creak and shudder continuously. The ice around the ship moved and broke throughout the night, battering the port side of the hull. All was quiet again until the afternoon of 30 September, by which time there were signs of spring with ten hours of sunlight per day and occasional temperature readings above freezing. A large floe was swept against the "Endurance"'s port bow and then gripped that side of the ship against the built-up ice and snow on her starboard beam. The ship's structure groaned and wracked under the strain. Carpenter Harry McNish noted that the solid oak beams supporting the upper deck were being visibly bent "like a piece of cane". On deck the ship's masts were whipping back and forth as their stepping points on the keel were distorted. Despite these disconcerting signs, Captain Frank Worsley noted that the strength of the ship's structure was causing the ice itself to break up as it piled against the hull – "...just as it appears she can stand no more, the huge floe weighing possibly a million tons or more yields to our little ship by cracking across...and so relieves the pressure. The behaviour of our ship in the ice has been magnificent. Undoubtedly she is the finest little wooden vessel ever built..." Despite this, the ship's decks were permanently buckled following this ordeal.