COOK STRAIT TIDES

Timaru Herald, Volume CXLII, Issue 20465, 9 July 1936, Page 13

COOK STRAIT TIDES

A KNOTTL PROBLEM effects of The weather The tricky tides experienced in Cook Strait are well known to all mariners, and it was therefore with much interest that those present at the half-yearly meeting of the New Zealand Companj’ of Master Mariners listened to Captain W. J. Keane, of the Marine Department, when he spoke on the effects on these tides of certain meterological conditions. Special reference was made by the speaker to the meterological conditions prevailing about the time when the Rangatira met with her mishap. After dealing with tides in general, Captain Keane explained the Cook Strait tides. He pointed out that normal functioning of the Cook Strait streams depends upon a normal tide wave proceeding around the New Zealand coast and any interference with this wave at any part of the coast—with the possible exception of the south-west half of the South Islandmust be reflected by the abnormal behaviour of the tidal streams in Cook Strait. This fact, no doubt, was the reason for the warning given in the “NeW Zealand Pilot,” which states: “The influence of heavy gales upon the tidal streams is felt when the disturbance is from 24 to 48 hours distant, and the influence of the current caused by the winds may prolong or relate the duration of the tidal streams by one to three hours.” “We have recently had demonstrated to us, unfortunately though forcibly,” he continued, “the undoubted effect of an intense storm system on the tides and tidal streams on the New Zealand coast generally, and in particular in the Cook Strait regions, and owing to the serious consequences of both the storm and the abnormal tidal conditions, Information has been obtained which allows us to connect up what has been found in practice with the laws governing these disturbed forces as far as we have been able to Interpret them. “Cook Strait can be said to be the nerve centre of the New Zealand tlda' system, and it would appear to be a matter for regret that the meagre information at present available has not been considerably augmented from the experience of master mariners who have navigated in these regions. It would be of scientific interest to know to what extent irregularities in these streams precede meterological changes or, on the other hand, how long before equilibrium is restored after such changes. It is not suggested that definite information regarding the expected behaviour of Cook Strait streams could be supplied to the navigator, but it is suggested that some attempt should be made by observations to connect up the vagaries of these streams with the meterological conditions existing when they are observed. “In view of the aids which have long been available for thick weather navigation, it appears incomprehensible that master mariners responsible for navigating under a system of exactitude made necessary by public convenience, should have no other aid at their disposal on which they can rely in thick weather than a compass. “If such warnings cannot be given with any certainty, then it appears that It Is most important to supply the navigator with such aids as to mak° the need of such Information unnecessary. Having regard to the volume of shipping entering Wellington Harbour athwart the fast-moving and irregular streams of Cook Strait, the provision of these aids Is of paramount importance for the safety of life at sea in these parts.”