Story: Charting the sea floor
Page 2 – First charts of New Zealand
New Zealand was discovered by Polynesian seafarers well before the arrival of Europeans. But they did not create written records, and this has meant that the first charts of New Zealand’s land and seabed were those drawn by European explorers.
Putting New Zealand on the world map
There is some debate about when New Zealand was first committed to a map. Parts possibly appeared on the world map of Jean Rotz, published in 1542 for King Henry VIII of England. A large southern land mass resembling Australia was shown with a distinct promontory, which some geographers have interpreted as New Zealand’s East Cape. However, evidence for this view is not strong.
The first time any part of New Zealand was outlined on paper was during Abel Janszoon Tasman’s voyage of 1642–43. Although he never stepped ashore, Tasman, aided by his pilot, the hydrographer Franz Jacobszoon Visscher, plotted New Zealand’s west coast from near Hokitika to Cape Maria van Diemen. That fragment of the coastline was to appear in atlases for the next 228 years.
Cook's remarkable chart
The now familiar long, narrow outline of New Zealand was initially drawn by Captain James Cook during his first voyage to the country, from 7 October 1769 to 1 April 1770. In just 175 days he sailed around the main islands, plotting the general pattern of the coast with amazing accuracy. There are errors, however. Banks Peninsula is shown as an island and Stewart Island is connected to the South Island.
Cook’s achievement was remarkable. His ship, the 30-metre Endeavour, was awkward to sail and he relied on a sextant and ship's clock for navigation. In places Cook was able to plot water depth, the location of rocks and the outline of sand banks. Some of his depth measurements, including those from Doubtful Sound, remained on hydrographic charts until well into the 20th century.
Chart to chart
The magnitude 8.1 earthquake of 1855 uplifted the entire Wellington peninsula and tilted it to the west. By comparing the 1849 chart, surveyed by the Acheron before the earthquake, with the 1903 chart by the Penguin, changes in water depth could be measured. Differences between the two charts show that the harbour entrance became shallower by up to 3.6 metres due to uplift and siltation. Without the 1855 chart there would have been no way of calculating these changes.
Early colonial mapping
Charts of New Zealand improved after surveys made by the French, British and other explorers who came after Cook. Much of their effort focused on bays, fiords and harbours – where ships took on supplies or were repaired.
Traders added to the hydrographic coverage of the country. The Snapper, a cargo vessel carrying flax, measured depth in Foveaux Strait. A need arose to chart harbours for the safe passage of immigrant ships. In 1826 Port Nicholson (Wellington Harbour) was surveyed twice. As coastal settlements sprang up, increased shipping saw greater demand for better charts. Between 1848 and 1851 the Acheron undertook the first systematic, detailed hydrographic survey of New Zealand.