CHARTING COAST

New Zealand Herald, Volume LXXI, Issue 21806, 22 May 1934, Page 6

CHARTING COAST

NEW SURVEYS NEEDED / (WORK FOR' THE ADMIRALTY rectifying deficiencies "All the New Zealand coast requires resurveying," said an Auckland master mariner yesterday, when, commenting on a report from Wellington that the Marine Department has received a communication from the British Admiraltv with reference to the undertaking of such a task. So far as Auckland is concerned the chief danger from inadequate surveys is in the vicinity of Cuvier Island, an important landfall to masters of vessels approaching the Hauraki Gulf from Panama or from the South. At a meet- ! ing of the Auckland Harbour Board last week it was decided to urge the Marine Department to have carried out without further delay the promised survey of that part of the coastline outside the Great Barrier Island and in the vicinity of Cuvier Island and leading/ to the channel between the Great Barrier Island and Cape Colville. The coastal charts have been compiled mainly from surveys made between 1849 and 1855 by H.M.S. Acheron and H.M.S. Pandora, and from 1903 to 1905 6y H.M.S. Penguin. The Acheron and the Pandora conducted what is known as a running survey along a large portion of the west coast of both "islands and their charts, are, therefore, incomplete. The survey made by the Penguin was more exhaustive, but was by no means fully comprehensive. Recent Auckland Surveys V The Hauraki Gulf was charted by 1 the Penguin in 1904, and it is not considered that the gulf proper is in urgent need of re-survey, but certainly, it is urged, the outer areas, particularly where overseas vessels make their landfalls, .should be charted again without delay. A hvdrographical survey of a complete nature would occupy several years. Such work is usually undertaken bv the Admiralty, which has trained men and up-to-date equipment, which are essential to the task. By arrancement •with the Auckland Harbour Board the .iVaitemata Harbour was resurveyed by , the Admiralty in 1911. Another important survey put in hand /by the Harbour Board was the charting by its own officials of the Manukau Bar in 1919. The bar, which is about four miles out to sea and is subject to fairly frequent changes, had not been surveyed since the Pandora did the work over 60 years earlier. The fyar was again charted in 1921 and in 1926, and a close watch is maintained to ensure that no major alterations go unrecorded. Thirty Years Out of Date The fact that New Zealand's coastal charting is inadequate is recognised by both the British Admiralty and the Marine Department, and, on most of the official charts, the British hydrographer draws the attention of mariners to defects in the surveys. Discrepancies in latitude and longitude are responsible for many errors. The coast charts prepared by the Acheron and Pandora are based on earlier longitude determinations; the Penguin's are based,/on the official longitude of the Dominion. Mariners are advised of these/''discrepancies in the New Zealand Nautical Almanac. Outside of casual surveys and various changes consequent upon the locating of some new rock or reef, New Zealand's official charts have remained untouched for about 30 years. There have been many complaints as to the lack of new information, and •while the masters of regular coastal traders may have become more or less accustomed to the deficiencies of their charts, the captains and officers of overseas ships have on many occasions expressed dissatisfaction with the charts at their disposal. An indication of the new material i which is continually being forwarded 'to the Marine Department may be obtained from several of the department's notices to mariners gazetted lately. In one case a rocky shoal with a least depth of two and threequarter fathoms, about 300 ft. long and 150 ft., wide, with depths of ten fathoms close round, was reported as located in Foyeaux Strait. In another case, reported to the Auckland Harbour Board yesterday, two clumps of conspicuous treqs on Bushy Poiiflt,/ Foveaux Strait, were charted in different positions from previous marine . advice. Use of Echometers Waipapa Point, inFoveaux Strait, near ■which the Tararua was wrecked in 1881, has a note beside it on the official chart stating that it is reported to lie about a mile further south tnan charted in 1924. A rather similar case has occurred in connection with Toby Rock, another ■well-known spot in the strait. It was announced a few days ago that the rock lies 340 degrees and about six cables from i,ts charted position. Earlier this month the Marine Department notified mariners that a rock, with a least depth of 18ft. at the lowest tides, had been located in the Stephens Island passage, Cook Strait. If the warships attached to the New Zealand Division of the Royal Navy were equipped with echometers and other instruments necessary for modern charting operations something might be done to rectify the position. The only ships on the New Zealand coast fitted iwitl* echometers are the Government steamer Matai and the express steamer Rangatira. Among the overseas ships carrying them is the Akaroa. New ships being built for trade between Great Britain and New Zealand will be equipped with echometers. It is, however, not the task of these ships to chart the local coast, and if they carry echometers it is largely for their own protection ___