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Endurance, the wooden vessel that Ernest Shackleton took to Antarctica in 1915, was not designed for harsh frozen waters – and the famed explorer was aware of this fact.
By Colin Barras
The remains of the Endurance, which sank in 1915
Science History Images / Alamy
One hundred and ten years have passed since Endurance, often hailed as the most robust wooden ship ever constructed, succumbed after becoming trapped in Antarctic sea ice. Recent evaluations indicate that Endurance was in fact significantly less durable than other polar vessels of its era, suggesting that Shackleton was cognizant of its limitations.
Shackleton had ambitious plans to cross Antarctica from the Weddell Sea to the Ross Sea, hoping to visit the South Pole en route. Yet, Endurance never reached the icy edges of Antarctica. Instead, in 1915, it became trapped in the Weddell Sea and ultimately sank, albeit with all crew members safely using the lifeboats.
Jukka Tuhkuri from Aalto University, Finland, participated in the Endurance22 expedition that located the shipwreck on the seafloor in 2022. Tuhkuri began to question the reasons behind the ship’s sinking, and upon investigating the history of similar polar vessels, he found a straightforward answer: Endurance lacked the strength of its counterparts.
During the late 19th and early 20th centuries, several ships were built specifically to navigate through sea ice. Many were designed with a more rounded shape and shallower keels, minimizing the likelihood of ice gripping the vessel’s hull. Inside, reinforced lower decks added to the ship’s structural integrity, creating box-like formations that bolstered the overall strength.
Endurance did not possess these design advantages. Its long, tall keel made it less resilient against the extreme conditions. Tuhkuri’s calculations showed that several polar ships of the era could endure compressional loads ranging between 1.7 to 2.7 times greater than Endurance. Additionally, the size of the engine compromised the lower deck’s support, leading to a vulnerability at the hull’s midpoint.
In his review of Shackleton’s letters, Tuhkuri found evidence that the explorer was aware of these weaknesses. In a correspondence to his wife just prior to departure, Shackleton mentioned that Nimrod, a ship from an earlier expedition, was sturdier. Nevertheless, he proceeded with the expedition. “He was prepared to take that risk,” Tuhkuri remarks.
As expected, Endurance ultimately succumbed to the intense pressures of the ice, becoming crushed and deformed until its keel was wrenched off, leaving a significant hole in its structure below the waterline.
By then, the narrative that Endurance represented the world’s strongest wooden vessel had taken root, potentially stemming from coverage in The Times. Shackleton seems to have endorsed this legend; however, the rationale behind this remains unclear. Tuhkuri notes that this contributes an intriguing layer to the saga of Shackleton’s tragic venture. “Endurance was a robust and heroic ship in a metaphorical context,” he observes. “Yet, from an engineering perspective, it fell short.”
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