Rescuers on Saturday reached a fishing boat with 26 people aboard trapped in ice near Antarctica and plan to use an unmanned underwater vehicle to assess the damage to it.

The U.S. Coast Guard icebreaker Polar Star traveled several hundred nautical miles through heavy ice to reach the Antarctic Chieftan.

Authorities said the Australian fishing boat suffered damage to three of its four propeller blades and lost its ability to maneuver after becoming stuck in the ice Wednesday.

Polar Star Commanding Officer Capt. Matthew Walker said in a statement that the conditions were more formidable than expected, with heavy snow and large icebergs.

"We are on scene and progressing well with the rescue," he said.

Once the Polar Star breaks the ice around the fishing boat, the Coast Guard crew will lower a remotely operated vehicle into the water for a better look at the boat's propeller blades.

The plan is then for the Polar Star to free the fishing boat, and, if necessary, tow it from the ice field. From there, the Coast Guard said, there are plans for the New Zealand fishing boat Janas to escort or tow the boat to the nearest safe harbor.

The 63-meter (207-foot) fishing boat is stuck about 900 nautical miles (1,666 kilometers) northeast of McMurdo Sound. It's licensed to catch Antarctic toothfish, a prized delicacy that's often marketed in North America as Chilean sea bass.

Mike Hill, the manager of New Zealand's Rescue Coordination Centre, said the hull of the boat remains undamaged and the crew are well provisioned and don't face any immediate danger.

Authorities at first said there were 27 crew members aboard but have now amended that to 26.