Tidal predictions anomalies investigated

21 March 2003

Land Information New Zealand is moving quickly to investigate possible anomalies with 2003 Gisborne tide predictions.

A report has been received that suggests Gisborne's 2003 high and low tide predictions (effective 1 January, 2003) may be up to an hour 'out', says John Spittal, Chief Topographer/Hydrographer for Land Information New Zealand (LINZ).

"Our 2003 predictions may be up to an hour early from what people will see when they go down to the beach.

Collection of new, high quality tidal data from a gauge sited in the harbour will enable us to determine whether or not an anomaly exists and if so generate more accurate predictions."

Any new predictions will be published in the 2003/4 Nautical Almanac and on the LINZ web site in June/July, says John Spittal.

"Predictions by their very nature can never anticipate future natural events with 100 percent accuracy. However, while differences between predictions and observations of up to an hour are considered small, they need to reflect the actual state of the tide as closely as possible. We'll be working hard to determine if a problem has occurred and if so make improvements.

Until then we ask users of our Gisborne tidal predictions to use them with caution."

LINZ has issued a Notice to Mariners to inform boaties that there are possible anomalies that need to be factored into their sailing times.

For further information please contact:

John Spittal
Chief Topographer/Hydrographer
Land Information New Zealand
Private Box 5501
WELLINGTON
PH: 04 471 6856
FAX: 04 471 6894
EMAIL: jspittal@linz.govt.nz