Rescue vessel maps Foveaux Strait

Rescue vessel maps Foveaux Strait

The NIWA research vessel Tangaroa, which rescued British rower Jim Shekhdar from the waters of the Southern Ocean earlier this week, had just finished mapping the shipping lanes of Foveaux Strait.

The survey, on contract for Land Information New Zealand (LINZ) and worth $3.8 million, covered more than 3000 square kilometres of shipping lanes throughout Foveaux Strait. It was carried out to ensure safe shipping in the area, especially for ships entering the port of Bluff, and will result in a new hydrographic chart.

The waters of Foveaux Strait are possibly the most difficult waters in the world to survey, and that includes the ice-riddled waters of Antarctica.

‘From a technical point of view, this survey was much more difficult than the shipping lane survey work we did for LINZ in Antarctica in 2001,’ said NIWA’s [the National Institute of Water & Atmospheric Research] marine project director Fred Smits. ‘Our biggest problem was the long ocean swell that can last for about a minute or more and reach a height of 6 metres. This upset the state-of-the-art equipment we used onboard which is based on missile technology.’

‘The waters around the complex coastline of the few small islands lying within the survey area were also very shallow, less than 6 metres deep in places, which requires the work to be done to a high level of accuracy.’

Mr Smits said NIWA and its subcontractor, the Australian company Thales, one of the largest marine survey companies in the world, worked closely with the American and Canadian manufacturers of the survey technology to overcome the equipment shortcomings. ‘This equipment is now the best in the world by far and NIWA and Thales are pleased to have made a major contribution to these developments,’ said Mr Smits. ‘It will make a big difference to the international marine survey community for years to come.’

‘We finished the survey work with Tangaroa, but we also used our coastal inshore vessel Kaharoa and the launch Pelorus to survey the shallow water just outside the surf zone. We had to meet the very strict standards set by LINZ. This requires being able to detect a rock measuring only 2 metres in diameter in water 40 metres deep,’ said Mr Smits.

In February next year Tangaroa will return to Antarctica under contract to LINZ to continue mapping shipping lanes in the area, a survey NIWA began in 2001. Based on the data collected by Tangaroa, LINZ made its first official chart of the Ross Sea to help fulfil New Zealand’s international obligation to ensure the safe passage and anchorage of any vessels in the Ross Sea Dependency. These charts are particularly important for the increasing number of research vessels and cruise liners entering the dangerous icy waters. ‘The detail and accuracy of the seabed information collected from the Foveaux Strait survey is very high, which will also be of great benefit to fisheries and scientific research. The local fishing industry has already expressed strong interest in the information for oyster distribution and habitat studies.’

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