Repairs to the guided missile cruiser USS Port Royal will continue in drydock into September — a month longer than previously thought — because the work has turned out to be more complicated than expected, the Navy said yesterday.

The 567-foot warship ran aground on coral and sand in 14 to 22 feet of shoal water a half-mile off Honolulu airport's reef runway on Feb. 5. It was stuck for four days.

Needed repairs include the refurbishment of the shafting, running gear and propellers, painting of the underwater hull, replacement of the bow-mounted sonar dome and its internal elements, and repairs to damaged tanks and superstructure cracks.

The Navy said work on the sonar dome — which received the most damage — "presented welding and technical challenges that have required more time than originally projected."

Additionally, the struts that support twin propulsion shafts were found to be out of alignment. "These complications have extended the repair schedule slightly," the Navy said.

The ship's rudders have been reinstalled and structural work on the ship's tanks and underwater hull has been completed, the Navy said. The three-week process to re-paint the hull, meanwhile, is scheduled to occur in September.

The majority of the Port Royal's underwater hull will be painted as it now sits in dock, but a small amount of the hull is covered by the blocks that the ship sits on.

As the painting progresses, Port Royal will be refloated and then redocked in a different position so the covered areas can be painted.

After leaving drydock, the ship will conduct several weeks of pierside testing to ensure all systems are operational, the Navy said. In addition, officials said extensive crew training is being conducted to ensure proficiency before the ship returns to full operational service in early October.

The cost of repairs is nearing $40 million, following $18 million in shipyard refurbishment prior to the grounding, the Navy said. The ship was on its first day of sea trials when the accident occurred.

The Navy also has spent more than $7 million to reattach nearly 5,400 impacted coral colonies and remove ocean floor rubble from the grounding site. Seven tugboats and two other ships were needed to pull the ship free.

The state on March 30 notified the Navy it intended to file a claim for damage to the reef and asked the Navy to perform emergency work to salvage surviving live coral and stabilize the reef.