“In appearance, the Endurance was beautiful by any standards. She was a barkentine—three masts, of which the forward one was square-rigged, while the after two carried fore-and-aft sails like a schooner. She was powered by a coal-fired, 350-hp steam engine, capable of driving her at speeds up to 10.2 knots. She measured 144 feet overall, with a 25-foot beam, which was not overbig, but big enough. And though her sleek black hull looked from the outside like that of any other vessel of a comparable size, it was not.”
“Her keel members were four pieces of solid oak, one above the other, adding up to a total thickness of 7 feet, 1 inch. Her sides were made from oak and Norwegian mountain fir, and they varied in thickness from about 18 inches to more than 2 1/2 feet. Outside this planking, to keep her from being chafed by the ice, there was a sheathing of stem to stern of greenheart, a wood so heavy it weighs more than solid iron and so tough that it cannot be worked with ordinary tools. Her frames were not only double-thick, ranging from 9 1/4 to 11 inches, but they were double in number, compared with a conventional vessel.”
“Her bow, where she would meet the ice head-on, had received special attention. Each of the timbers there had been fashioned from a single oak tree especially selected so that its natural growth followed the curve of her design. When assembled, these pieces had a total thickness of 4 feet, 4 inches.”
“But more than simple ruggedness was incorporated into the Endurance. She was built in Sandefjord, Norway, by the Framnaes shipyards, the famous polar shipbuilding firm which for years had been constructing vessels for whaling and sealing in the Arctic and Antarctic. However, when the builders came to the Endurance, they realized that she might well be the last of her kind—as indeed she was—and the ship became the yard’s pet project.”
“She was designed by Aanderud Larsen so that every joint and every fitting cross-braced something else for the maximum strength. Her construction was meticulously supervised by a master wood shipbuilder, Christian Jacobsen, who insisted on employing men who were not only skilled shipwrights, but had been to sea themselves in whaling and sealing ships. For luck, when they put the mast in her, the superstitious shipwrights placed the traditional copper kroner under each one to insure against its breaking.”
“[Endurance] was the strongest wooden ship ever built in Norway—and probably anywhere else—with the possible exception of the Fram.”
“However, there was one major difference between the two ships. The Fram was rather bowl-bottomed so that if the ice closed in against her she would be squeezed up and out of the pressure. But since the Endurance was designed to operate in relatively loose pack ice she was not constructed so as to rise out of pressure to any great extent. She was comparatively wall-sided, much the way conventional ships are.”
— Alfred Lansing, Endurance: Shackleton’s Incredible Voyage
Shackleton. 