Workers at the Pearl Harbor shipyard undocked the cruiser Port Royal yesterday as the Navy wraps up nearly $40 million in repairs — a milestone in the warship's return to service after an embarrassing grounding near Honolulu International Airport's reef runway in February.

Combined teams of BAE Systems and Pearl Harbor Naval Shipyard engineers and technicians worked alongside Port Royal sailors on the replacement of the 567-foot ship's bow-mounted sonar dome; refurbishment of the shafting, running gear and propellers; painting of the underwater hull; and on structural repairs to the ship's tanks, and cracks in the superstructure, the Navy said.

The guided missile cruiser ran aground on coral and sand in 14 to 22 feet of shoal water a half-mile off Honolulu airport's reef runway on the night of Feb. 5. It was stuck for four days and returned to drydock on Feb. 19.

The nearly $40 million in repairs followed $18 million in shipyard refurbishment immediately before the grounding. The ship was on its first day of sea trials when the accident occurred.

Repair work will continue pierside, the Navy said. Additionally, the ship's crew will conduct several weeks of "extensive pierside and under way testing to ensure all systems are operational," officials said.

A misinterpreted navigation system, a sleep-deprived skipper, faulty equipment and an inexperienced bridge team led to the grounding of the Port Royal, according to a Navy Safety Investigation Board report.

Capt. John Carroll, the ship's skipper, had only 4 1/2 hours of sleep in 24 hours, and 15 hours of sleep over three days as he pushed to get the warship under way after shipyard repairs, the report states. He was at sea in command for the first time in nearly five years.

The 9,600-ton cruiser's fathometer, which measures water depth, was broken, and both radar repeaters, or monitors, on the bridge were out of commission.

A shift in the ship's navigation system led to erroneous information on the ship's position. The switch from a Global Positioning System to a gyroscope caused a 1.5-mile discrepancy in the ship's position and set off alarm bells that were continuously disregarded, according to the safety board.

During the transfer of personnel back to shore that night using a small boat, the operations officer took a binocular bearing to the harbor landing from the boat deck and noted a discrepancy. He tried unsuccessfully to radio others and then headed back to the bridge, where he realized the cruiser was in the wrong spot.

The safety board report states that at 8:03 p.m., the Pearl Harbor ship was "soft aground" with the bow's sonar dome on the reef a half-mile south of the reef runway.

Waves forced the ship firmly onto the reef as the crew tried to free it. "Backing bell" and "twist" maneuvers using one screw, or propeller, failed.

The board found many equipment malfunctions and human errors, but said there were enough working sensors and visual cues to prevent the grounding.

"Bridge watch team, navigation, and (Combat Information Center) team did not work together to assess situation and keep the ship from standing into danger," the report stated.

The report said the ship unknowingly ended up shifting two miles to the east.

Carroll was relieved of his command soon after the grounding. He appeared at a Navy hearing on the grounding and was given "nonjudicial punishment for dereliction of duty and improper hazarding of a vessel," the Navy said in June.

Along with Carroll, executive officer Cmdr. Steve Okun appeared at the hearing and was given nonjudicial punishment for dereliction of duty, the Navy said.

Two officers and an enlisted sailor appeared at a separate hearing and also were given nonjudicial punishment for dereliction of duty and improper hazarding of a vessel, the Navy said. Their names were not released.

The Navy, in coordination with the state, has spent more than $7 million stabilizing the reef at the grounding site by reattaching thousands of coral colonies and removing 250 cubic yards of rubble.