History & heritage  |  8 Jan 2019

A new journey of discovery has unravelled the science behind an incredible feat of celestial navigation by Akaroa-born Antarctic explorer Frank Worsley.

An international group of researchers has used Worsley’s original logbook to analyse the voyage of a small lifeboat, the James Caird, across 1500 kilometres of wild sub-Antarctic sea in 1916.

Their conclusions are published in Volume 32 of Records of the Canterbury Museum, the museum’s annual research publication.

The logbook is part of the museum’s significant collection on Antarctic exploration.

In his home town, Worsley’s skills and unquenchable thirst for adventure are also celebrated in an exhibition at Akaroa Museum while a bust of the navigator stands near the main wharf.

Worsley's amazing Antarctic voyage was born out of desperation.

Today, it is viewed as one of the most remarkable feats of seamanship in history.

The main ship of the Imperial Trans-Antarctic Expedition, the Endurance, was crushed by pack ice in October 1915, stranding its crew – led by Sir Ernest Shackleton – on the ice.

The James Caird sets out for help.

The crew of the James Caird.

After camping out until April 1916, the 28 expedition members eventually reached Elephant Island in three lifeboats. With winter closing in, carpenter Harry McNish converted the seven-metre-long James Caird for open sea travel. Six men, including Shackleton, Worsley and McNish, then set out for South Georgia Island – home to whaling stations – to seek help.

The trip took more than two weeks, with Worsley’s job as navigator complicated by the rough conditions.

He needed to check the boat’s position by the sun but it was seldom seen.

He also had to estimate the longitude of the starting position. If this was wrong, the crew could overshoot South Georgia Island and all could be lost.

The research paper by Lars Bergman (Sweden), the late George Huxtable (Britain), Bradley Morris (United States) and Robin Stuart (New Zealand) provides an introduction to the principles and methods of celestial navigation used by Worsley to successfully complete the voyage.

The paper also answers several key questions over the source materials and assumptions enabling Worsley’s longitude estimate.

Remarkably, all the expedition members were eventually rescued.

Stuart says replicating the calculations has underlined the extraordinary feat of navigation.

“Worsley had to take the sights and manually perform the reduction calculations sitting on ballast rocks in a small boat heaving on ocean swells,” he says. “Yet, for that critical 14-day period, we did not find a single error.

“Without Worsley’s superlative skills as a navigator, Shackleton’s expedition might be remembered as a tragedy rather than the epic tale of Antarctic survival we know it as today.”

Stuart and Bergman have also used Worsley’s logbook to examine the possible location of the wreck of the Endurance.

That research was prompted by an international science expedition studying ice shelves in the Weddell Sea that planned to locate and survey the wreck.

The 45-day Weddell Sea Expedition, which includes scientists from the University of Canterbury, has recently left Penguin Bukta in Antarctica, heading for the Larsen C Ice Shelf.