The bad luck that has dogged Chinese team Sanya in the Volvo Ocean Race struck again on Thursday when a rudder snapped, causing the boat to take on water while ahead on leg five.

Sanya, skippered by Mike Sanderson of New Zealand, sustained the damage a few hours after a ploy to move south had put them in charge in the journey from Auckland to Itajai in Brazil.

Three to four tonnes of water flowed into the compartment at the back of the boat and, after shutting the watertight compartment, the crew worked to plug the gap and make the boat sea-worthy again.

"Our priority now is just to make sure everyone is safe," said Sanderson who must decide whether to attempt a repair at sea or to head to land, probably back in New Zealand.

"What happened is unbelievable. I'm lost for words. It's just really sad and once again it was nothing to do with what we were doing in terms of sailing the boat. The rudder just snapped."

Sanya are last overall after suffering two previous setbacks earlier in the race.

Within hours of the start of leg one from Alicante in November a collision blasted a huge hole in the structure of the boat, meaning they had to be shipped to the restart in Cape Town.

On the second leg they were leading by a huge margin when a key element of the rigging broke, forcing them to detour to Madagascar.

Camper/Team New Zealand, third overall, took over the leg lead from Sanya on Thursday followed by Groupama of France. Overall leaders Telefonica are fourth but still well placed with over 5,500 nautical miles to the finish.

Overall standings after four legs:
1 Telefonica (Spain) 122 points
2 Groupama (France) 107
3 Camper/ETNZ (Spain/New Zealand) 104
4 Puma (United States) 83
5 Abu Dhabi (United Arab Emirates) 55
6 Sanya (China) 25