The U.S. Navy has acknowledged that one of its hospital ships may have collided with the USS Arizona World War II memorial in Pearl Harbor.

The incident occurred early May 27 as the USNS Mercy was being guided out to sea by a pair of tugboats. The floating dock to the white memorial building that spans the mid-portion of the sunken battleship USS Arizona was struck, damaged and subsequently removed. The site is expected to remain closed to visitors until Thursday as repairs take place.

Military.com first reported the accident after the wife of an eyewitness reported that the Mercy collided with the memorial. Photographs she supplied showed the ship sailing dangerously close to the structure. The Navy initially suggested one of the tugboats may have struck the memorial. In its statement, however, the service confirmed the Mercy may have hit the structure.

"As the Mercy turned to head out to the channel, the ship may have made contact with the floating dock leading to the USS Arizona Memorial," it said in a statement the next day. "Strong prop wash from the ship pushed the floating dock and access structure (brow) approximately ten feet toward the memorial, damaging handrails and the dock's infrastructure."

Workers are repairing the dock and assessing the underwater mooring system of chains and anchors, the Navy said. The sunken battleship and the hospital ship weren't damaged, and nobody was hurt, the service said.

"We are hoping to have all repairs done by June 3 so the memorial can be reopened to visitors June 4," Navy Capt. Stan Keeve, commander of Joint Base Pearl Harbor-Hickam, said in the statement.

The USS Arizona Memorial is the final resting place of most of the ship's 1,177 crewmen who were killed during the Japanese surprise attack on Pearl Harbor on Dec. 7, 1941, according to the National Park Service, which manages the site. The accident involving the Mercy came just days after the Memorial Day weekend, a busy time of the year for the memorial, which receives as many as 4,350 visitors a day.

The hospital ship left the port later in the day en route to a planned four-month exercise in the Asia-Pacific region known as the Pacific Partnership 2015.
Because the Mercy is part of the service's Military Sealift Command, the ship doesn't have a traditional Navy command structure. Uniformed military personnel run the vessel's hospital, known in naval parlance as a military treatment facility, or MTF, while civil service mariners operate the ship itself and are responsible for navigation, deck operations and engineering duties.

While Navy Capt. Melanie Merrick is the commanding officer of the ship's medical treatment facility, Thomas Giudice is the captain of the ship itself. A retired enlisted sailor and current civilian mariner, he was named master of the USNS Mercy in November 2013 when the vessel was activated to support emergency relief efforts in the Philippines following Typhoon Haiyan.

At the time of the accident, the Mercy was under the direction of two tug boats tasked with guiding the vessel out of the harbor. The tug boat captains -- civilian contractors who work for the Honolulu-based Navy contractor P&R Water Taxi - haven't been identified.

It's also unclear what role the harbor pilot played in the incident. The harbor pilot, who also hasn't been named, is charged with helping ships enter and exit the port. He or she typically does so by boarding the ship and helping to guide it through the waters by communicating with the tug boat captains.
The Military Sealift Command is leading the Navy's investigation.

Meanwhile, the U.S. Coast Guard, part of the Homeland Security Department, is also conducting a so-called marine casualty investigation. The review will seek to determine what caused the accident and identify any violations of law or regulation.

-- Brendan McGarry can be reached at Brendan.McGarry@military.com