SAN DIEGO (NNS) -- In a rusty hulk of a barge beside dry dock on Naval Base San Diego's Mole Pier, the source of much of the Navy's sophisticated ship stealth technology waits for its next wave of classified experiments.
The result of the combined efforts of the Navy, the Defense Advanced Research Projects Agency (DARPA) and Lockheed Martin, Sea Shadow (IX 529) is nearing its second decade of service as the premier test platform for ship stealth and experimental technologies.
Sea Shadow is used to test advanced hull forms and structures, automation for reduced manning, sea keeping and signature control, said Paul Chatterton, Naval Sea Systems Command program manager.
In the early 1980s, the vessel was built modularly under tight secrecy by different manufacturers and assembled inside the Hughes Mining Barge (HMB), at Redwood City, Calif. There, the HMB would be moved out to sea in the dead of night and halfway submerged, to let Sea Shadow out to be tested without being overly exposed to public observation.
"It was never intended to be mission-capable," said Chatterton.
And so it was never designated as "USS," but contrary to what some might believe, it is listed in the Navy's inventory as a miscellaneous craft.
The radically sleek, angled sides of the vessel show the origins of similarly sloped sides and superstructures of the Arleigh Burke-class destroyers and the forthcoming DD-X class destroyers, said Chatterton.
Part of Sea Shadow's unique shape, its Small Water-plane Area Twin Hull (SWATH) design, isn't all that new. SWATH hull forms have been used for more than 30 years by many countries in ferry designs due to the very good stability inherent in the concept.
Sea Shadow doesn't have traditional rudders to steer with, said Chatterton. Aft stabilizers and forward canards on the inboard side of its submerged twin hulls control steering. Combined with the angled sides, this also helps the ship remain stable even in very rough water of up to sea state five, which means waves of up to 18-feet high.
T-AGOS 19-and-23-class oceanographic ships have inherited the stabilizer and canard method to help perform their stability-sensitive surveillance missions.
At only a bit over 160-feet-long, Sea Shadow doesn't have much room for a large crew. In fact, with only 12 bunks aboard, the maximum she's ever taken to sea at once is 24. With only one small microwave oven, a refrigerator and table, creature comforts plainly aren't what the ship is about.
"At sea, we have a four-person watch team," said Chatterton. "Three stand watch on the bridge, and one is available as a rover. We stand a six-hour-on, six-hour-off rotation with the other half of the normal eight-person crew."
Chief Engineer Tony Furrh said the bridge's displays enable a watchstander to cycle valves, transfer fuel, take suction from the sea or do almost anything else that needs doing, all remotely.
Lessons learned from Sea Shadow have affected current ship designs, equipment and concepts and will continue to well into the future, said Chatterton.
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