The Sea Shadow sits inside the Hughes Mining Barge. General Services Administration/U.S. Navy

One of the most unusual ships ever built at General Dynamics NASSCO will be auctioned off by the federal government, which has no use for a huge barge that helped to secretly recover pieces of a Soviet submarine that sank during the Cold War.

The General Services Administration is selling both the Hughes Mining Barge and the experimental Navy ship it houses, the decommissioned Sea Shadow. The vessels are moored at the National Defense Reserve Fleet in Suisun Bay, Benica.

The 324-foot submersible barge was built at NASSCO in the early 1970s as part of Project Azorian, a highly classified attempt by the Central Intelligence Agency to retrieve K-129, a diesel sub that mysteriously sank 1,560 miles northwest of Hawaii in 1968. The sub reportedly was carrying three nuclear missiles.

The CIA separately arranged for Howard Hughes to build the Glomar Explorer, a 619-foot ship that supposedly was to be used for deep sea drilling. But a report released by the CIA says that the vessel was designed to grab all or part of the sub, which would be pulled up from the seafloor and hidden inside the barge.

There are conflicting accounts about whether the CIA mission succeeded to any significant degree.

The barge, which has a large dome, was later mothballed in San Francisco. But in 1982 the Navy transferred the vessel to a Lockheed Martin plant in Redwood City, where it served as a drydock for the construction of Sea Shadow, a stealth ship that was used to test naval technology. The barge also was used to hide Sea Sparrow during part of its sea trials off Southern California. Sea Shadow operated at night, so that it couldn't been seen by satellites, or people operating at sea. After the test program ended, both vessels were transferred to the reserve fleet.

Various attempts have been made to make at least Sea Shadow part of a museum exhibit. But those efforts have failed. GSA is accepting bids on the ships through the end of next week. Currently, five bids have been made. The highest: $99,075.

The Cesar Chavez under construction at NASSCO in December. NASSCO
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INVITATION: On Saturday, May 5, NASSCO will launch the last of the 14 T-AKE dry cargo ships that it has built for the Navy. The christening and launch will occur at NASSCO's yard in Barrio Logan in San Diego. The public is invited to attend. The ceremony starts at 7:30 p.m.

Story sources: General Services Administration, Central Intelligence Agency, U.S. Navy, Lockheed Martin, National Security Archive, Federation of American Scientists, Wikipedia.