Efforts to rescue the crew from the stricken Russian fishing vessel Sparta have been hampered by icy conditions in the southern ocean.
The 48m vessel, with 32 crew on board, issued a distress call around 3am on Friday after hitting ice. The incident caused a 30cm hole in the hull, 1.5m below the water line. The boat was taking on water and listing 13 degrees.
Yesterday, a Royal New Zealand Air Force (RNZAF) C130 Hercules dropped extra pumping equipment and fuel to the vessel, after a seven-hour flight from Christchurch.
The Hercules was returning today and due back in New Zealand tonight.
However the crew on board Sparta have requested more equipment to help repair the damage to the boat's hull.
Sparta is stranded next to the Antarctic ice shelf, about 2000 nautical miles (3704 kilometres) south east of New Zealand.
The Rescue Coordination Centre New Zealand (RCCNZ) tasked three nearby vessels to assist Sparta, but all three have been hampered by heavy sea ice.
One, the New Zealand vessel San Aspiring, was released from the rescue yesterday after its crew determined the more than 470 nautical mile (NM) journey was too dangerous.
The Norwegian vessel Sel Jevaer is only 19NM away but is currently hemmed in by ice and unable to proceed. Sparta's sister ship, Chiyo Maru no. 3 is slowly making its way towards the stricken vessel but is still days away.
RCCNZ Search and Rescue Mission Coordinator Neville Blakemore said the crew was continuing to pump water from the ship using the on-board pumping equipment and the one delivered yesterday.
"They are keeping ahead of the water ingress using two pumps," Mr Blakemore said.
"But they are having difficulty in trying to fix a patch to the damaged part of the hull because they need to stop one of the pumps to do this, and then the water level creeps up again."
Mr Blakemore said Sparta's stability was currently the number one priority for the rescue operation.
"With help days away at least, we need to keep the crew on board Sparta where they have their best chance of survival.
"The crew has manoeuvred the vessel alongside the ice shelf and attached mooring lines to the ice. They have also deployed their life rafts which are alongside Sparta.
"They have told us they need more equipment to assist with repairs and securing the vessel."
Mr Blakemore said the ship's agent was sourcing the equipment and RCCNZ would coordinate its delivery.
Sparta's owner has commissioned the South Korean icebreaker Araon to go to Sparta to offer assistance. Araon left New Zealand just after midnight and is expected to take about eight days to reach Sparta.
Weather conditions in the area remain calm.