Though her hull looked from the outside like that of any other vessel of a comparable size, it was not. She was designed for polar conditions with a very sturdy construction. Her keel members were four pieces of solid oak, one above the other, adding up to a thickness of , while its sides were between and thick, with twice as many frames as normal and the frames being of double thickness. She was built of planks of oak and Norwegian fir up to thick, sheathed in greenheart, an exceptionally strong and heavy wood. The bow, which would meet the ice head-on, had been given special attention. Each timber had been made from a single oak tree chosen for its shape so that its natural shape followed the curve of the ship's design. When put together, these pieces had a thickness of .