When the wreck of Ernest Shackleton’s Endurance was found almost 10,000 feet below the surface of the Antarctic Weddell Sea in March 2022, it was only 4 miles from its last known position, as recorded by Endurance’s captain and navigator Frank Worsley. In November. 1915
This is an astonishing degree of accuracy for a position determined by mechanical tools, book-length numbering tables, pen and paper.
The expedition looking for the ship explored an underwater area of 150 square miles – a circle with a diameter of 14 miles. No one knew how accurate Worsley’s position calculation was or how far the ship could travel while sinking.
But as an historian of Antarctic exploration, I wasn’t surprised to learn how accurate Worsley was, and I guess those looking for the wreck weren’t surprised either.
National Library of Australia via Wikimedia Commons
Navigation was key
Endurance left England in August 1914 and the Irish Shackleton hoped to be the first to cross the Antarctic continent from one side to the other.
But they didn’t even land in Antarctica. The ship became stuck in sea ice in the Weddell Sea in January 1915, forcing people to abandon ship in tents pitched in the frozen ocean nearby. The force of the ice slowly crushed the Endurance, sinking it 10 months later and setting off an incredible – and almost unbelievable – saga of survival and navigation for Shackleton and his crew.
Shackleton’s leadership itself has become legendary, as has his commitment to ensuring that no man was lost from the group under his command, although three members of the 10-man expeditionary group in the Ross Sea did die.
Less well known is the significance of the navigational skills of the 42-year-old Worsley, a New Zealander who served for decades in the British Merchant Marine and the Royal Navy Reserve. Without him, Shackleton’s story of survival would probably have been very different.
Underwood and Underwood/Corbis via Getty Images
Time marking
Navigation requires determining the ship’s position in latitude and longitude. Latitude is easy to determine by the angle of the sun above the horizon at noon.
To determine longitude, it was necessary to compare the local noon – the moment when the Sun was at its highest point – with the actual time elsewhere, where the longitude was already known. The main thing was to make sure that the time measurement for this other place was accurate.
It was quite difficult to carry out these astronomical observations and make the corresponding calculations on land. In the ocean, when several fixed points of land are visible, this was almost impossible in inclement weather.
Thus, navigation was largely dependent on “correct counting”. It was the process of calculating a ship’s position using a previously determined position and including estimates of how fast and in which direction the ship was moving. Worsley called it “nautical calculation of courses and distances”.
Longing for the earth
When the Endurance was crushed, the crew had to flee or die on an ice floe drifting somewhere in the Southern Ocean. In April 1916, six months after the Endurance sank, the sea ice they had camped on began to melt. 28 people, their remaining equipment and supplies were loaded into three lifeboats – “James Caird”, “Dudley Docker” and “Stancomb Wills”, each of which is named after the main sponsors of the expedition.
Worsley was in charge of making sure they landed. As the journey began, Shackleton “saw Worsley as navigator, balancing on the gunwale of the Dudley Docker, with his arm around the mast, ready to grab the sun. He got his sighting and we were looking forward to him getting the sight right.”
To do this, he compared his measurements with the time on the chronometer and wrote tables of calculations.
Last hope for survival
Once they managed to arrive at a small rocky strip called Elephant Island off the coast of the Antarctic Peninsula, they were still in danger of starvation. Shackleton believed that the only hope for survival lay in getting help from somewhere else.
Worsley was ready. Before the Endurance was wrecked, she “worked out courses and distances from the South Orkney Islands to South Georgia, the Falklands and Cape Horn, respectively, and from Elephant Island to the same places,” he recalled in his memoirs.
The men used parts from other lifeboats to strengthen James Caird for the long sea voyage. Every day, Worsley “followed closely the rising of the sun or the stars, in order to correct his chronometer, on the accuracy of which our lives and the success of our journey would depend.”
On April 24, 1916, Worsley received “the first sunny day with a clear enough horizon to get a scope to evaluate my chronometer”. On the same day, he, Shackleton, and four other men set sail on the 22.5-foot James Caird, carrying a Worsley chronometer, navigational books, and two sextants, which were used to determine the position of the sun and stars.
boat trip
These people, in this tiny boat, sailed from one rock in the Southern Ocean to another, faced with strong winds, strong currents and choppy waters that could severely confuse them or even sink them. The success of this journey depended on Worsley’s absolute accuracy, based on observations and estimates he made in the worst possible environmental conditions, while being sleep deprived and frostbitten.
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They spent 16 days of “high-fighting churning waters” as the boat sailed through some of the most dangerous sea conditions in the world, experiencing “mountain” waves, rain, snow, sleet and hail. During this time, Worsley was able to obtain only four reliable information about the location of the boat. The rest was “a hilarious guessing joke” to determine where they were blown by wind and waves and adjust the steering accordingly.
The stakes were huge: if he missed South Georgia, the next land would be South Africa, 3,000 miles further across the more open ocean.
As Worsley later wrote:
“Navigation is an art, but words cannot properly name my efforts. … Once, maybe twice a week, the sun smiled with a sudden wintry shimmer through the clouds broken by a storm. If ready for it, and smart, I caught it. The procedure was as follows: I looked out of our hole – the precious sextant pressed against my chest so that the waves would not fall on it. Sir Ernest stood under the canvas with a chronometer, a pencil and a book. I shouted “Stop!” and knelt on the uneven bars – two men supported me on both sides. I lowered the sun to where the horizon should be, and as the boat desperately jumped up on the crest of a wave, I guessed the height and shouted: “Stop!”. Sir Ernest took his time and I processed the result. Then the fun began! Our fingers were so cold that he had to interpret his wobbly figures—my own were so illegible that I had to recognize them from memory.”
On May 8, they saw floating algae and birds, and then spotted land. But they arrived in South Georgia during a hurricane, and for two days they had to fight the wind on the island they had spent weeks trying desperately to get to.
Finally, they went ashore. Three of the six men, including Worsley, traveled through uncharted mountains and glaciers to reach the small settlement. Worsley joined the lifeboat to pick up the other three. Later, Shackleton organized a ship to collect the rest of the men from Elephant Island, all of whom survived their unimaginable hardships.
But the key to it all, like the recent discovery of the wreck of the Endurance, was how Worsley fought the desperate conditions and yet repeatedly managed to figure out where they were, where they were going, and how to get there.
