Pearl Harbor Naval Shipyard has put the damaged Navy guided missile cruiser Port Royal into drydock.

The 9,600-ton Port Royal, which was drydocked between October and January for regular maintenance, is expected to be in drydock for months of repairs to damage incurred after it ran aground off Honolulu International Airport's reef runway on Feb. 5. The bow sonar dome and struts, shafts and propellers at the stern were heavily damaged.

The grounding occurred at about 8:30 p.m. on the first day of sea trials after leaving drydock and while the ship was transferring sailors, contractors and shipyard workers to shore via small boat. The Navy is investigating the grounding, and some have speculated the Port Royal was east of the spot where such transfers normally occur.

The ship underwent $18 million in repairs during the recent drydocking at Pearl Harbor. The hull was repainted, the propellers and hubs were replaced, the rudders and sonar dome were repaired, and the shafts were refurbished.

Workers in the shipyard, the state's largest industrial employer, are expecting lots of overtime as repairs are made. The Navy said a cost estimate for the damage has not been determined.

Port Royal was drydocked on Oct. 15 with the frigate Crommelin. Docking the ships together, instead of separately, saved the Navy $100,000 and allowed repairs to be made sooner to Crommelin.