Endurance (1912 Ship) - Design and Construction

Design and Construction

Designed by Ole Aanderud Larsen, the Endurance was built at the Framnæs shipyard in Sandefjord, Norway and fully completed on December 17, 1912. She was built under the supervision of master wood shipbuilder Christian Jacobsen, who was renowned for insisting that all men employed under him not just be skilled shipwrights, but also be experienced in seafaring aboard whaling or sealing ships. Every detail of her construction had been scrupulously planned to ensure maximum durability, for example every joint and every fitting cross-braced each other for maximum strength.

She was launched on December 17, 1912 and was initially christened the Polaris (eponymous with Polaris, the North Star). She was 144 feet (44 m) long, with a 25 feet (7.6 m) beam and weighed 350 short tons (320 t). Though her black 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 85 inches (2,200 mm), while her sides were between 30 inches (760 mm) and 18 inches (460 mm) 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 30 inches (760 mm) thick, sheathed in greenheart, a notably strong and heavy wood. Her bow, where she 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 is natural shape followed the curve of her design. When put together, these pieces had a thickness of 52 inches (1,300 mm).

Of her three masts, the forward one was square-rigged, while the after two carried fore and aft sails, like a schooner. As well as sails, Endurance had a 350 horsepower (260 kW) coal-fired steam engine capable of driving her at speeds up to 10.2 knots (18.9 km/h; 11.7 mph).

By the time she was launched on December 17, 1912, Endurance was perhaps the strongest wooden ship ever built, with the possible exception of the Fram, the vessel used by Fridtjof Nansen and later by Roald Amundsen. However, there was one major difference between the ships. The Fram was bowl-bottomed, which meant that if the ice closed in against her she would be squeezed up and out and not be subject to the pressure of the ice compressing around her. 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.