New Study Reveals Why the Endurance Sank

British polar explorer Sir Ernest Henry Shackleton established his place in the annals of history after ensuring the survival of his entire crew following the shipwreck of Endurance in 1915. A new paper sheds light on the state of the infamous vessel—and what Shackleton knew of it before setting off.

Jukka Tuhkuri, a polar explorer and researcher specializing in ice mechanics and arctic marine technology at Finland’s Aalto University, has revealed that Endurance was not as sturdy as widely believed, and that Shackleton knew about its structural shortcomings. His work adds nuance to one of the most famous survival stories over 100 years since the explorer’s death and three years since he and the rest of the Endurance22 mission found the shipwreck.

A dramatic turn of events

In August 1914, Shackleton and his crew set sail from England. The Imperial Trans-Antarctic Expedition aimed to achieve the first overland crossing of the Antarctic continent. The plan was for a team to hike from the Weddell Sea over the South Pole to the Ross Sea, but the main expedition ship Endurance got stuck in pack ice in 1915 and was eventually crushed, sinking below the water in November. The 28 members of the crew survived on the ice before using boats to reach Elephant Island. From there, a small team including Shackleton sailed 800 miles (1,300 km) to South Georgia Island to get help. By September 1916, the whole Endurance crew had been rescued without losing a single life.

“Even simple structural analysis shows that the ship was not designed for the compressive pack ice conditions that eventually sank it,” Tuhkuri said in an Aalto University statement. “The danger of moving ice and compressive loads — and how to design a ship for such conditions — was well understood before the ship sailed south. So we really have to wonder why Shackleton chose a vessel that was not strengthened for compressive ice.”

According to Tuhkuri, Endurance is widely believed to be the strongest polar ship of its time, but with one failing—a problem with the rudder—that would lead to its unfortunate end. By combining technical analysis and archival research in a study published today in the journal Polar Record, the researcher revealed this to be a flawed perception.

“Endurance clearly had several structural deficiencies compared with other early Antarctic ships,” he said. “The deck beams and frames were weaker, the machine compartment was longer, leading to serious weakening in a significant part of the hull, plus there were no diagonal beams to strengthen the hull. Not only does this challenge the romantic narrative that it was the strongest polar ship of its time, but it also belies the simplistic idea that the rudder was the ship’s Achilles’ heel.”

Why did Shackleton sail on Endurance?

Despite investigating Shackleton’s diaries, personal correspondence, and other communications from the crew, Tuhkuri isn’t sure why Shackleton decided to sail with Endurance. He knew about the ship’s problems—Tuhkuri said that the explorer complained about it to his wife before the start of the expedition, wishing for his previous vessel.

“In fact, he had recommended diagonal beams for another polar ship when visiting a Norwegian shipyard. That same ship got stuck in compression ice for months and survived it,” Tuhkuri continued.

As such, the paper prompts an interesting question. Was the ship “ill-fated,” or were bad calls at the heart of it? Tuhkuri, however, chose to leave it unanswered. While he hopes his research will contribute a novel point of view to our understanding of the vessel, he says that it doesn’t try to diminish Shackleton and his crew’s accomplishment.

“We can speculate about financial pressures or time constraints, but the truth is we may never know why Shackleton made the choices that he made. At least now we have more concrete findings to flesh out the stories,” he concluded.