Sub needs stealth coating repaired during overhaul
Two others in its class have lost some sonar shielding.
KITTERY, Maine - The USS Virginia shed pieces of its sonar-absorbent skin while on patrol, giving the hull a pockmarked appearance as the submarine arrived for repairs at Portsmouth Naval Shipyard.
The stealthy sub could become easier to detect by enemy sonar if it lost too much of the special coating. But the Navy insists that the sub never lost enough of the material to rise to that level and that it has moved aggressively to fix the problems in newer models of nuclear-powered attack submarines.
"We've been aware of the issues, we're making improvements in the process, and we're seeing results already," said Alan Baribeau, spokesman for the Naval Sea Systems Command in Washington. There has been "no measurable impact on the ship's performance," he said.
Since the Navy took delivery of the Virginia in 2004, five others like it have been built and put into service.
During the summer, the Pentagon's director of test and evaluation described a November 2009 review that found the finish peeling off in big swatches "up to hundreds of square feet."
The most serious problems for the so-called anechoic coating have been limited to the first three subs in that class, the Navy said. The coating on the hull of the Virginia will be repaired during a regularly scheduled 14-month overhaul at Portsmouth Naval Shipyard.
The Virginia was off-limits to public viewing last week. But there were several missing pieces visible on the 377-foot-long sub when it arrived in Kittery on Sept. 1. The repair process includes cutting away any loose pieces of coating before replacing the material, the Navy said.
Cmdr. Timothy Salter, the sub's skipper, declined to comment.
The material is likened to the stealth coating on fighter jets and bombers that absorbs radar's electromagnetic waves; the anechoic tiles on submarines absorb sound waves from sonar.
They help to provide stealth to modern submarines.
"If you have a significant portion of a submarine's exterior surface lacking sound-absorbent material, it's at greater risk of being detected and tracked in a way that can compromise its survivability," said Loren Thompson, a defense analyst with the Lexington Institute.
While the Navy has used anechoic tiles for years, it instituted a new process with the Virginia in which the ship is coated with a "special hull treatment," Baribeau said. It is described in some literature as a rubberlike substance, but the Navy will not reveal details because they are classified.
Problems with the coating on the Virginia were noted in 2007. The Navy immediately began working on changes to the application process, he said.