The Russian fishing vessel stranded in Antarctica remains in a precarious position as the crew battles to stop more water leaking in through its damaged hull.
A rescue operation was sparked after the Sparta struck a submerged iceberg east of the Ross Sea about 3am Friday, stranding its 32 crew next to the Antarctic ice shelf, about 3700km southeast of New Zealand.
The 48m vessel suffered a 30cm hole in its hull, 1.5m below the water line, and was listing 13 degrees.
Three ships were making the days-long journey towards the stricken vessel, including an icebreaker, while a New Zealand air force C130 Hercules yesterday dropped off extra pumping equipment and fuel after a seven-hour flight from Christchurch.
Sparta's crew advised overnight that temporary patches attached to the damaged section of hull had failed and the boat was again taking on water.
But by this morning, the crew had again managed to stop the ship taking on water.
Rescue Coordination Centre New Zealand mission coordinator Dave Wilson today said the ship remained in a precarious position, which highlighted the importance of the air force's mercy dash.
"This equipment has enabled them to get on top of the water ingress again, and they will now be working to fix the patches more securely."
Mr Wilson said the stabilisation work was vital as any rescue would be days away and the vessel was providing shelter for the crew.
"They have life rafts but with the conditions down there, it's much safer for them if they can wait for rescue on board their vessel."
A South Korean icebreaker commissioned by the Sparta's owners left New Zealand just after midnight to offer assistance.
The Araon left was expected to take about eight days to reach Sparta.
Two other vessels, the Sel Jevaer and Chiyo Maru No. 3, were continuing towards Sparta but their progress was being hampered by heavy sea ice.
The vessels were expected to take several days to reach the Sparta.
Another vessel, the San Aspiring, has been released from the rescue operation after its crew reported conditions were too difficult for it to proceed.
Mr Wilson said the ship was about 870km from Sparta but would have had to travel much further to reach the stricken vessel because there was no direct line through the ice.
"They confirmed the journey would take too long and would potentially put their own crew in danger."