The crew of international oil company OMV's seismic survey vessel Polarcus Alima has decided to play it safe and return to Port Otago for a crew change.
Recent bad weather has hampered the 89m-long vessel's operations while the crew surveys the ocean floor in the Great South Basin, to the east and south of Southland.
A scheduled crew change was due to be carried out by helicopter on Wednesday but could not be done safely because of poor weather conditions, OMV New Zealand managing director Peter Zeilinger said.
"The decision was made to bring the vessel to port to safely conduct the routine crew change and to use the opportunity to restock provisions and fuel.
"The Polarcus Alima is a state-of-the-art seismic vessel, built to the highest safety, performance and environmental standards, but we have to recognise the safe operating conditions dictated by weather," he said.
"So far, performance has been excellent and the survey is on schedule, which gives credit to the planning and execution skills of the team involved on board and in the office."
OMV and its joint venture partners were nearing completion of the programme to acquire more than 4000sq km of 3-D seismic data in exploration permits 50119 and 50120, he said.
The survey is scheduled to be completed by mid-April.
Permit holders are OMV NZ Ltd (operator for the seismic programme, 18%), PTTEP NZ Ltd (18%), Mitsui Australia Ltd (14%) and Shell GSB Ltd (50%).
Mr Zeilinger said Shell joined the joint venture in August 2011, and would take over as operator of the permits at the conclusion of the 3-D seismic programme.
The boat was due to depart Fryatt St Wharf last night.
