The crew on board the stricken Russian ship Sparta have requested more equipment to help repair damage to the boat's hull.
The 48m vessel is stranded in the Southern Ocean about 2000 nautical miles south-east of New Zealand.
Ice tore a 30cm hole in the ship's side early on Friday morning.
Dave Wilson of the Rescue Co-ordination Centre Search says temporary patches covering the hole failed on Saturday and more water poured in, but the crew worked through the night to repair it.
Three nearby boats were sent to assist the Sparta but heavy sea ice has hampered their efforts; one has had to abandon the rescue mission for safety reasons and the nearest boat is still days away.
The centre says the crew's best chance of survival is staying on board, so keeping the ship stable is the top priority.
It says the crew has requested more equipment to help with repairs.
An icebreaker that left Christchurch just after midnight on Saturday is not expected to reach the Sparta for about eight days.
Equipment and fuel delivered
An RNZAF Hercules dropped equipment and fuel to the Sparta.
The aircraft made three passes over the fishing vessel to drop off a pump, pipes, other equipment and fuel on Saturday night.
Air Force squadron leader Andy Scott says the crew are in good spirits.
The Sparta has a 30cm hole in the side 1.5m below the water line and is on a 13 degree list but its crew has been doing all it can to lighten the vessel enough to correct the list.
The Sparta sent out a distress call at about 3am on Friday (NZT), which was passed to New Zealand by Norway.
The ice surrounding the ship is estimated to be up to 1.5m thick.