COOK STRAIT TIDES

Press, Volume XCIX, Issue 29324, 1 October 1960, Page 4

COOK STRAIT TIDES

Maximum Of Four Knots

Tidal streams in Cook Strait can reach speeds- up to four knots at the surface, according to measurements made by Mr A. E. Gilmour, of the New Zealand Oceanographic Institute. In the latest .issue of the New Zealand Journal of Geology and Geophysics, Mr Gilmour, says the current in Cook Strait is essentially turbulent and extends from one shore to the other in the narrows. -

Measurements were made from the Navy fleet auxiliary Isa Lei and the Matai during surveys for a Cook Strait power cable by the Electricity Department The strong tidal currents through the strait happen because the tides at opposite ends are out of phase, says Mr Gilmour. Several different methods were used to measure the currents, including electrical methods (using telegraph cables), aerial observation. measurements from an anchored ship, and measurements at the bed of the strait Currents just below the surface flowed at roughly the same rate as surface currents, but measurements about a foot aboVe the sea floor showed the velocity of the current was about a third of the velocity on the surface.