A New Zealand research vessel is dropping 120 robots into the sea between here and Chile as part of a worldwide project to check changes in the ocean's environment.

The National Institute of Water and Atmospheric Research ship Kaharoa will leave Wellington Harbour tomorrow for the 65-day trip.

The Argo instruments, or floats, that cost $15,000 each, were part of an observation system for the Earth's oceans.

Twenty-seven countries were involved in the project to drop 3000 aluminium profiling floats, which are 1.5m high and 20cm in diameter, into the sea around the world.


Dean Roemmich from Scripps Institution of Oceanography said the floats dropped as far as 2000m before rising back to the surface, profiling the temperature, pressure and salinity of the water on the way. The data was transmitted via satellite every 10 days to scientists on shore.

"It's used for looking at the state of the global ocean and initialising prediction models...so things like predicting the next El Nino or climate change over the coming decades," he said.

There had been 11,000 papers written from this type of research over the last 10 years.

About 3500 floats were collecting data worldwide at the moment.

They were "indigestible" to hungry sharks, Dr Roemmich said.

"We have seen some shark bites on returned instruments - they'll have a go at it, but I don't think they'll try more than once."

As well as the price of the robotic units, it costs about $10,000 a day to run the ship.

Footing the bill for the New Zealand project was mostly from the United States, from the University of Washington and Scripps Institution of Oceanography, as well as funding from Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO) and a contribution from Niwa.


On board Kaharoa will be US, Australian, and New Zealand equipment. During the voyage, 12 floats will be deployed for CSIRO, 52 for the University of Washington, 49 for Scripps and two for Niwa.