Shackleton knew his doomed ship wasn’t the strongest before sailing

It has been 110 years since endurance, often described as the strongest wooden ship ever built, flowed after being trapped in sea ice near Antarctica. But a reassessment of evidence reveals that endurance was in fact much lower than the other polar vessels of the time – and also suggests that the chief of the expedition Ernest Shackleton was aware of his shortcomings.

Shackleton had planned to travel the Antarctica of the Weddell Sea at the Ross Sea, visiting the South Pole on the way. But endurance has never reached the frozen shore of Antarctica. In 1915, he became stuck in ice in the Weddell Sea and sank – although all crew members survived disaster using the ship’s rescue canoes.

Jukka Tuhkuri at the University of Aalto, Finland, was involved in the Endurance22 expedition which discovered the wreckage of the ship on the seabed in 2022. Tuhkuri began to wonder why such a robust ship flowed. But while he explores the history of polar ships built at the time, he realized that there was a simple explanation: endurance was not particularly strong.

At the end of the 19th and early 20th century, a handful of boats were built to cope with sea ice. Some were more oval than a standard ship, with a less deep keel. The two features make it more difficult for sea ice to obtain a strong purchase on the sides of a ship, which slides the ice under the hull instead. Inside the ships, during this time, the lower bridges gave the hull greater rigidity, because they crossed from left to right of the ship over its entire length, creating box -shaped structures in the ship that strengthened it.

Endurance had none of these features. It was a relatively long ship with a high keel. Tuhkuri calculated that, as a result of this design, some of the other polar vessels of time could resist between 1.7 and 2.7 times more compression load than endurance. In addition, the ship of the ship was so large that the lower bridge could only take place over the length of the ship, ending in the machine room and creating a weak point in the hull where there was no structure in the shape of a reinforcement box.

When Tuhkuri examined Shackleton’s correspondence, he discovered that the explorer knew these problems. In a letter to his wife shortly before putting himself in Antarctica, Shackleton said that Nimrod, a ship he had used during an earlier expedition to Antarctica, was stronger. He still continued the shipment. “He was ready to take the risk,” says Tuhkuri.

As could be expected, endurance could not face the overwhelming pressures of sea ice. The boat was pressed and folded, and finally its keel was torn to leave a gaping hole under the driving of water.

But at that time, the myth that endurance was the strongest wooden ship in the world was emerged, its origin was perhaps an article in TimeAccording to Tuhkuri, and Shackleton perpetuated the idea. We don’t know why he did, but it’s a detail that says Tuhkuri adds color to the history of Shackleton’s unhappy expedition. “Endurance was a strong and heroic ship in a poetic sense,” he says. “In the sense of engineering, unfortunately, this was not the case.”