When the wreck of Ernest Shackleton’s Endurance was found nearly 10,000 feet below the surface of Antarctica’s Weddell Sea in March 2022, it was just 4 miles from its last known position, as Endurance captain and navigator Frank Worsley noted in November. 1915.
This is an amazing level of accuracy for positions determined with mechanical tools, reference number tables, and pen and paper.
The ship’s search expedition has searched an area of 150 square miles of seabed – a circle of 14 miles. No one knows the exact calculation of Worsley’s position, or how far away the ship was when it sank.
But as a historian of Antarctic exploration, I was not surprised to learn how accurate Worsley was, and I imagine that the search for the wreck was not.
Navigation is key
The Endurance had left England in August 1914, with the Irishman Shackleton hoping to be the first to cross the Antarctic continent from one side to the other.
But he never landed in Antarctica. The ship got stuck in sea ice in the Weddell Sea in January 1915, forcing the men out of the ship into tents pitched on the frozen sea nearby. The force of the ice slowly destroyed the Endurance, sinking it 10 months later, and kicking off what would become an incredible – and almost unbelievable – saga of survival and navigation by Shackleton and his crew.
Shackleton’s own leadership has become the stuff of legend, as has his commitment to ensuring that no one is lost from the group he leads – even though three members of the group of 10 expeditions in the Ross Sea perished.
Less well known is the importance of the navigational skills of Worsley, 42, a New Zealander who spent decades in the British Merchant Navy and Royal Navy Reserve. Without him, the story of Shackleton’s survival would have been very different.
Time to signal
Navigation requires determining a ship’s location in latitude and longitude. Stars are easy to find from the angle of the Sun above the horizon during the day.
Longitude is needed to compare the local noon – the moment when the Sun is at its highest point – with the actual time at another location for which the longitude is known. What is important is that the time measurement for the other location is accurate.
Making these astronomical observations and performing the resulting calculations is quite difficult on land. In the ocean, with few visible weak points, in the middle of bad weather, it is almost impossible to do.
So navigation is largely dependent on “dead reckoning”. This is the process of calculating a ship’s position by using a previously determined position and incorporating an estimate of how fast and in which direction the ship is moving. Worsley called it “a mariner’s calculation of courses and distances.”
The goal is to land
When the Endurance is crushed, the crew must beg for safety, or die on an ice floe adrift somewhere in the Southern Ocean. In April 1916, six months after the Endurance sank, the sea ice where they camped began to break up. The 28 men and their remaining equipment and supplies were loaded into three lifeboats – the James Caird, Dudley Docker and Stancomb Wills – each named for the expedition’s main donor.
Worsley was responsible for taking them ashore. When the voyage began, Shackleton “saw Worsley, as navigation officer, balancing himself on Dudley Docker’s gunwale with his arm around the mast, ready to snap the sun. He got the observation and we waited patiently while he did the scene.
To do that, he compared his measurements with the time on a chronometer and a table of written calculations.
The last hope for survival
After arriving at a small rock strip called Elephant Island, off the coast of the Antarctic Peninsula, he was still starving. Shackleton believed that his only hope of survival was to seek help from elsewhere.
Worsley was ready. Before the Endurance was crushed, he had “worked out the course and distance from the South Orkneys to South Georgia, the Falklands and Cape Horn, respectively, and from Elephant Island to the same place,” he recalled in his memoirs.
They used parts of other lifeboats to strengthen the James Caird for the long sea voyage. Every day, Worsley “watched closely for the sun or the stars to appear, to correct my chronometer, with an accuracy on which the life and success of the voyage would depend.”
On April 24, 1916, Worsley got “The first clear day with a horizon clear enough to see to rate my chronometer.” On the same day, he, Shackleton and four other men left on board the 22.5-foot James Caird, carrying Worsley’s chronometer, navigation book and two sextants, used to fix the position of the Sun and the stars.
Boat trip
These people, in this small boat, move from one rocky point in the Southern Ocean to another, facing strong winds, strong currents and water that can push them astray or even drown them. The success of this journey depends on Worsley’s absolute accuracy, based on observations and predictions made in the worst environmental conditions, when sleep-deprived and frostbitten.
The men spent 16 days of “high strife in the midst of tumultuous waters,” as the vessel navigated some of the world’s most dangerous sea conditions, experiencing “mountainous” swells, rain, snow, ice and hail. During that time, Worsley was only able to complete four improvements in the ship’s position. The rest is a “guess puzzle” to determine where the wind and waves have taken, and set the rudder.
The stakes were high – if he missed South Georgia, the next land would be South Africa, 3,000 miles away on more open seas.
As Worsley wrote later:
“Navigation is an art, but words fail to give the right name. … Once, perhaps twice, a week of smiling sun suddenly flashes in the winter, through the terrible clouds. If I am ready, and smart, I am caught. This procedure : I peered out of our burrow – the precious sextant cuddled on my chest to prevent the sea from falling in. Sir Ernest stood under the canvas with a chronometer, pencil, and book. I shouted ‘Stand by,’ and knelt in thwart – two people held me up on either side. I brought the sun down to where the horizon should be and as the boat leaped frantically up the crest of the waves, snapped a good guess at the height and shouted ‘Stop.’ Mr. Ernest took his time and I worked on the results. Then the fun began! Our fingers were so cold that he had to interpret my illegible figures, so I had to know them by heart.
On May 8, he saw seaweed and birds floating, and then appeared on land. But he had arrived in South Georgia in the middle of a hurricane, and for two days had to fight being driven by the wind to the island he had been trying to reach for weeks.
At last they came to land. Three of the six men, including Worsley, climbed unmapped mountains and glaciers to reach the small settlement. Worsley joined the returning rescue ship to pick up the other three. Shackleton then organized a ship to collect the rest of the people from Elephant Island, all of whom had survived unimaginable hardships.
But the key to it all, and indeed the new discovery of the Endurance wreck, is how Worsley fought his desperate circumstances and still time and time again managed to figure out where he was, where he was going and how he got there.