COASTAL CHARTS.

Dominion, Volume 4, Issue 1082, 22 March 1911, Page 6

COASTAL CHARTS.

ACCURATE OR OTHERWISE? THE TRUE POSITION. A telegram yesterday from New Ply mouth announced that Captain Newton, harbourmaster at that port, had discovered that tho position of the harbour, .is published in (he New Zealand Nautical Almanac, was three and three-quarter miles out of position. There is not quite the significance in this statement that at tho first impression there would seem to be. The Nautical Almanac, to which reference is made, though a very useful book for mariners and shipping firms, does not take the place of tho chart, and. is ,'carceiy an authority which tea captains would accept iu that way. It is a yearly publication, which is intended rather as n supplementary issue to tho New Zealand I'ilot. All the latest information for mariners is published in it —such details as that referring to harbour lights, port regulations, lighthouses, wharfage matters, etc. The latitude and longitude of places are given approximately, and tho information is rather to indicate in a ready fashion- where the places on the Admiralty chart may be found.' Unless, of course, the position is given to a second, it will be determined from a more detailed authority, either from tho Naval chart or from tho figures supplied by the Surveyor-General. Such is_ the explanation of Captain Blackburne, Nautical Adviser. In the case of New Plymouth, the Admiralty harbour chart gives the position as much the same as in the Almanac, though (ho coast chart, by which all masters would navigate in that vicinity, ie very little at variance with the position as defined by the Surveyor-General. It should perhaps be explained that the Lands Department possesses the very latest instruments, and is able to detertninato very accurately the position of any locality, and very often is called upon to supply such information to harbour boards. Each year, when the Almanao is being compiled, the Nautical Adviser requests each port to send in' information which will render the details as accurate, as possible. The following paragraph appears in the preface to the Nautical Almanac:— "As an explanation of the differences which sometimes occur between the position (latitude and longitude) of places mentioned in this work and the position as given on the Admiralty charts, it may bo as well to state that tho positions, when given to the nearest second-of an arc, are the result of determinations by tho Surveyor- • General of the Dominion, and they occasionally differ from the position of place as given'on the Admiralty chart by over 3 minutes in the longitudeas at Timaru." In the case of New Plymouth, nppaiv ently the Surveyor-General's figures have not been included in the Almanac, though, no doubt, this will now be done. All this,' however, only serves to emphasise the comparative inaccuracy of the charting of the New Zealand coast, or those portions of it, rather, which were untouched by Captains Coombe and Dawsan when they were engaged on a marine survey under a joint arrangement between the Admiralty and the New Zealand Government. Unfortunately, the portions surveyed are insignificant • com- , pared with those left as the chart of 50 years ago gives them. The localities surveyed were, roughly, the Hamaki Gulf, Auckland Harbour, and the portion of the East Coast lying between tha Gulf of Taurahga, Wellington Harbour, and a small portion of the West Coast of the South Island. Tho cost of this work to tho New Zealand Government was, approximately,' .27500 a year, and the aggregate sum amounted to about ,£39,000. The Government then decided to carry out the purvey itself and in 1907 engaged Captain Sinclair, but the Admiralty failed to supply a ship, and Captain Sinclair declared that no vessel in New Zealand waters was suitable. The latest decision is that the Terra Novn, on its return from the Antarctic regions, shall be, if possible, chartered for the work. Meanwhile the coast'of New Zealand is being worked on what is known as a "running" survey, on a chart nearly fifty years old. The feeling among some of the marine insurance companies is that if these inaccuracies in. the definitions of the coast are found to be as bad as the recent discovery of tho Cambrian in relation to the Three Kings might lead those interested to suppose, it will occasion a feeling of uneasiness which will probably lead to an increase in rates. The underwriters are loth to move hastily, but; (especially in regard to tho coastal trade) they will have to protect their interests. They have been under the impression always that' the charts have been correct. A prominent sea captain, interviewed, said that no danger could bo said to exist in a general, way in regard to shipping, unless, of course, a vessel unused to tho coast approached at night time, or ft navigator were enveloped for any length of time in a fog. The navigation of the coastal fleets was not dangerous, or even risky.