Andrey Kulish, manager of the ship's San Diego-based owner, Sedna Industries, said his crew were winning their battle to stay afloat but said it would be at least seven days before the South Korean icebreaker Aaron could reach the vessel.
Sedna commissioned the Aaron about midnight on Saturday after the Rescue Co-ordination Centre released the New Zealand vessel San Aspiring from the operation when its crew reported conditions were too difficult to proceed.
The San Aspiring was 870km away from Sparta but would have had to travel much further to reach the vessel, because there was no direct line through the ice.
Mr Kulish said crew had made excellent progress in getting water out of the ship after receiving extra pumping equipment and fuel from a Royal New Zealand Air Force C130 Hercules on Saturday.
Eighteen crew members who evacuated the ship on liferafts were now back on board and helping with the salvage.
He said arrangements were being made with the RNZAF to drop materials to help with the repairs.
Mr Kulish said the affected hold was the ship's freezer, which would need to be disassembled before repairs to the hole could take place.
The ship also needs to unload at least 120 tonnes of fuel to another vessel to make it lighter so it can be raised and engineers can assess the damage.
The Sparta could still be operated but Mr Kulish added: "Of course we will know if there is more damage when the ship is raised.
"At this moment, the water has stopped and of course there are leaks. We will have to offload the fuel and then we can weld it from the outside."
Search and rescue mission co-ordinator Dave Wilson said the Sparta's position was precarious but the crew had made good progress.
The crew had advised that temporary patches they attached to the damaged section of hull had failed and the boat was again taking on water - but yesterday reported that the leaks had again been stopped.
"This highlights the importance of the RNZAF's mission in delivering the pumping equipment yesterday. 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."
The rescue co-ordination centre said three vessels had gone to the Sparta's aid but all were facing difficulties with heavy sea ice 1.5m thick.
One vessel was only 35km away, but was hemmed in by ice and unable to move towards the Sparta.
Members of Kiwi Rescue Flight 629 delivered a water pump to the ship at the weekend.
"Their pumps were coping with getting the water out, but if one of those pumps broke down they would be in dire straits," said Flight Lieutenant James Anderson, captain of the aircraft.
"They seem to be in good spirits. That's what we got told by the captain."
