May 21, 2009: After eight weeks in a Persian Gulf shipyard, the 24,000 ton American amphibious ship (the USS New Orleans, LPD 18), had its hull, fuel tank and ballast tanks repaired. The damage occurred last March 20th, when the New Orleans collided with a submerged submarine (the 7,000 ton USS Hartford, SSN 768) in the narrow Straits of Hormuz. Fifteen sailors aboard the sub were injured, while a fuel tank on the LPD was torn open, and 25,000 gallons of fuel oil got into the water. Both vessels returned to port under their own power. The accident happened at 1 AM, local time. The commander of the sub was later relieved of duty. When underwater, the submarine is responsible for avoiding collisions with surface ships.
The Straits of Hormuz, and the Persian Gulf in general, is a busy waterway, and collisions are fairly common, which the reason there was a large enough dry dock available nearby to make repairs to the New Orleans. The Persian Gulf is 989 kilometers long, and the average depth is 50 meters (maximum depth is 90 meters). A U.S. SSN is about 18 meters from the bottom of the sub (the keel) to the top of the sail (the box like structure on top of the sub). This makes the one or two American SSNs operating in the Gulf yet another navigation hazard. When SSNs are damaged in an area like this, only emergency repairs are made locally. Given the sensitive nature of the technology used in subs, final repairs are done at a yard that can handle classified material (either in the U.S. or a NATO ally.)