A secret chapter in American naval research could soon reach an ignoble close when a rusty barge and its once-classified contents leave Suisun Bay for the scrap heap.
Slipping through the sea like a black mirage on catamaran legs, the 164-foot Sea Shadow looks like something Darth Vader might fly. It is the world's only ship built to be invisible, assembled secretly in Redwood City in 1985 by the U.S. Navy and contractor Lockheed Martin at an estimated cost of $50 million.
Sea Shadow's purpose was to test radar-cloaking technology and other naval engineering innovations. Many of its breakthroughs can be seen in present-day Navy warships.
Even at nearly 30 years old, Sea Shadow remains the most radical ship afloat.
"You take the propellers off it and that thing could really double as a spaceship in any science fiction movie," said Bruce Ecker, a San Pedro photographer who has documented the ship. "It looks secret. You want to go and rattle the doorknob on it just to see if you can get in."
Sea Shadow's rise and fall is a rare peek into the vast and complicated workings of the American military industrial machine. It is just one of many marvels hatched by the Pentagon to give the nation an edge in warcraft, then cast aside when the battlefield changed, the money ran out, or the admirals simply wanted to try out something else.
In this case, that quest for an edge produced a ship that really seized the imagination.
Yet Sea Shadow's days are numbered: In an auction set to close Friday, the Navy hopes to find a bidder who will buy the ship merely for its scrap value. This comes after the Navy spent six fruitless years trying to give the ship to a museum.
"While several letters of interest were received our only disposition option is dismantling and recycling," said Navy spokesman Christopher Johnson.
Sea Shadow was conceived during the waning years of the Cold War, when America was looking for a tactical edge against Russia. The Pentagon directed billions of dollars into stealth technology, particularly the ability to hide weaponry from enemy radar.
The first successful product from this laboratory was the F-117 Nighthawk, a Stealth attack jet built by Lockheed Martin, which became operational in 1983. Two years later, Lockheed got another secret contract to apply the same ideas to America's naval fleet, and Sea Shadow was born.
The primary goal was to find out if an entire oceangoing ship could be made to vanish from enemy radar, as well as to test innovative ship controls and hydrodynamic principles.
At Lockheed Martin's secret island shipworks along a San Francisco Bay slough, near Highway 101 in Redwood City, the company repurposed another clandestine relic to start the project.
The Hughes Mining Barge-1, or HMB-1, is a one-off submersible barge built as part of a 1974 CIA mission to lift a sunken Russian submarine from the Pacific Ocean seafloor. It was a companion for the Glomar Explorer, a much larger ship that did the heavy lifting.
The barge had one purpose: To hide the giant claw that the Glomar Explorer would use to grab the Russian sub. When the mission took place, the barge was towed out to sea and submerged. Its retractable roof was opened, and the Glomar Explorer maneuvered above it to lift the claw into its belly.
Because Sea Shadow also had to be kept under cover, the barge as long as a football field would prove to be the perfect factory floor and long-term garage.
Phantom on the water
The stealth ship was actually built in sections by different contractors so that none would know its entire shape. The sections eventually had to be welded together, and as each became ready, it was lowered through the retractable roof on the barge. Then the roof was closed up tight again to avoid the prying eyes of Russian spy satellites arcing overhead.
Sea Shadow's most notable design feature is its angular shape. Head-on, it looks like the letter "A" skimming across the water on its two splayed legs.
The design is a drastic departure: Virtually every other warship at sea has vertical sides to accommodate lots of crew and weapons. Sea Shadow's sides tilt in toward each other, which restricts interior space it has bunks for just 12 but also scatters radar signals.
The ship is coated with radar-absorbent materials, the details of which remain classified, said S.K. Gupta, a retired Lockheed engineer who was Sea Shadow's test director from 1988 to 1995.
"We operated with impunity," said Gupta, who lives in Pleasanton. "We could take anybody down at night."
The ship, of course, was not truly invisible to the naked eye. But it was difficult to see at a distance even in daytime because of its low profile. At night, its flat-black paint made a visual sighting nearly impossible, and its shape and surface coating made it, indeed, invisible to radar.
Gupta described one night exercise where Sea Shadow was able to sneak up on an aircraft carrier, pop one of its flush-fitting deck hatches, and fire three flares at the heavily defended carrier. Until the hatch opened, Sea Shadow went undetected.
"They could barely see where the flares came from, but by the time we had closed the hatch, we disappeared again," he said.
In another test, engineers placed a common aluminum soda can atop Sea Shadow's narrow black deck. The "enemy" radar in the exercise could pick up the soda can, but not Sea Shadow, Gupta said.
During the early years of its operational career, the ship was based in San Diego and generally kept inside the barge. When a test was planned, the barge was towed out to sea, then partially submerged so Sea Shadow could slip out and always at night.
Many of these tests involved assessing the seaworthiness of Sea Shadow's radical shape. Gupta's job included seeking out bad weather to test the ship's performance in a condition called Sea State 5, which involves waves as big as a two-story house.
The ship passed easily, he said. Because its mass was centered over two long catamaran legs, it was far more stable than the conventional ships that usually escorted it.
"We basically had a great time watching all the other support ships getting tossed around," Gupta said. "We were just going through the water like cutting through butter."
As far as the public knows, Sea Shadow was never equipped with weapons because it was merely a test platform, and never engaged in any actual military missions. But as a test vehicle, it was successful. Some of its stealth architecture can be seen in contemporary Navy ships such as the Arleigh Burke-class of guided missile destroyers.
From marvel to relic
Nothing the size of Sea Shadow can stay secret forever, and the Navy eventually decided to unveil the ship on Easter weekend in 1993, off Santa Cruz Island in Southern California. The reason for this has never been revealed. It may simply be that major testing with the ship was done.
The program officially ended in 1994, although the ship was periodically reactivated for additional testing until it was officially stricken from the fleet in 2006. For part of that period, the ship and its barge were berthed at Alameda Naval Air Station, and a stunned public occasionally caught sight of Sea Shadow making a daytime trip out to sea via the Golden Gate.
The Navy has had the ship on "donation hold" since 2006 in hopes of finding a museum to display it. It has always been offered as a package with the barge, perhaps because this makes transportation easier.
In 2009, the Navy advertised in the Federal Register that it wanted to give the pair away. The USS Ranger Foundation in Portland was the only interested bidder. But the group, which is still negotiating to obtain the Navy's USS Ranger aircraft carrier, had other motives.
It wanted to trade the barge as a dry dock for Washington State ferries, in return for shipyard services for the aircraft carrier, said Peter Ogle, the foundation's president. That deal fell through, and the foundation never completed an application to acquire the package.
As compelling as Sea Shadow is, it may not be an ideal museum piece, said Rich Pekelney, a board member of the Historic Naval Ships Association who lives in San Francisco. Its stealthy shape makes it cramped inside, complicating potential tours.
More important, the only self-supporting museum ships are those with a long service history or a distinguished past, like the aircraft carrier USS Midway in San Diego or the Liberty ship SS Jeremiah O'Brien in San Francisco.
Sea Shadow, on the other hand, was never even blessed with an official "USS" title.
Yet the ship is significant, Pekelney said, which is why he recruited Ecker to photograph it. With the Navy's blessing, the two spent five days aboard Sea Shadow last summer. Ecker, a commercial photographer, volunteered his time and used advanced panoramic equipment to shoot 360-degree views of the ship's interior.
As a result, Internet visitors can now pan through almost every square inch of Sea Shadow at www.hnsa.org/seashadow/.
"From the public's perspective, Sea Shadow is just this incredibly exotic-looking shape," said Pekelney. "But the more I dug into it, the more I came to realize we really got a lot out of that program, even from what I can tell as an outsider."
Scrapping Sea Shadow may not prove any easier than finding a museum to take it.
The Navy's terms require the ship and its barge to leave the Mothball Fleet within 30 days of the close of the auction. The barge can be repurposed for commercial use, but Sea Shadow must be scrapped.
Not only that, it must be scrapped within six months of auction, within the United States, and amid full-time surveillance by the government.
Johnson, the Navy spokesman, said these conditions are standard practice whenever a naval vessel is scrapped. He declined to speculate on what would happen if no bidder emerges.
In the end, Ecker's photographs might be the closest this shadowy ship ever gets to a museum.
"All these things are pieces of steel floating in salt water. They will not last," Ecker said. "In 100 years, somebody may value these images."