Say goodbye to the Glomar Explorer

Most of our posts here on the OTO company blog discuss what we do at OTO and what we can do for our clients. Every once in a while, though, we like to share something a little more unusual.

As we come to the end of a year, many people find themselves reflecting on prominent events from the year, often including the passing of prominent people. We lost one gray lady with a very mysterious past this year. Engineers, ship aficionados, and Cold War fans may shed a tear over this, but the former Glomar Explorer has been sold for scrap. This is a shame, not only because of the ship’s nearly unbelievable history, but also because in 2006 the American Society of Mechanical Engineers (ASME) designated this technologically remarkable ship a historic mechanical engineering landmark.


A product of the depths of the Cold War, the Glomar Explorer ranks alongside the Titanic, the battleship Bismark, and the USS Nautilus (the first nuclear-powered submarine) as one of the most unique and storied ships of the 20th Century. In a story that reminds us that the truth is often stranger than fiction, the Glomar Explorer was designed and built at great expense for a single purpose – to recover a sunken Soviet Navy submarine, the K-129, from the bottom of the Pacific Ocean.

The gestation of the Glomar reads like something out of a spy novel, and indeed, she was ultimately the product of some wishful thinking by the CIA’s Special Activities Division. The K-129, one of the Soviet navy’s most modern ballistic missile submarines, had sunk in 1968 about 1,500 miles northwest of Oahu after an onboard explosion. Although she contained potentially valuable intelligence sources such as cryptographic equipment and nuclear technology, there was no way to recover this possible treasure from the seabed more than three miles below the surface—it was far too deep for divers and adequate remote operated vehicles just didn’t exist yet.

An aerial starboard bow view of a Soviet Golf II class ballistic missile submarine underway.
An aerial starboard bow view of a Soviet Golf II class ballistic missile submarine similar to the K-129 (courtesy Wikipedia).

Then someone had the clever idea of simply hoisting the submarine to the surface. Of course, the idea was simple…. as it eventually turned out, the execution was nearly as complicated as a manned space flight.

From there, as the proverb goes, the weird went pro. The rest of the Explorer’s gestation involved a strange crew of intelligence analysts, eccentric industrialists, oilfield roughnecks, and a dream team of engineers from companies as diverse as Global Marine, then the undisputed leader in deep-ocean undersea exploration, and Lockheed Martin’s “Skunk Works” aerospace bureau. The whole undertaking was given the codename of Azorian, possibly an intentionally misleading reference to the US Navy submarine USS Scorpion, which sank with all hands near the Azores Islands in May 1968. Project Azorian ultimately cost over $800 million at the time ($3.8 billion in 2015 dollars).

Global Marine (now part of the offshore drilling corporation Transocean) had pioneered most of the methods and technologies used in the then-new field of deep-water oil drilling during the 1960s, including the drilling ship Glomar (from “Global Marine”) Challenger, used for the Deep Sea Drilling Program that provided evidence for continental drift. They were the logical choice to design and help operate the specially built salvage ship.

For a cover story, the CIA turned to the eccentric multimillionaire defense contractor (and real-life inspiration for Tony Stark) Howard Hughes. With Hughes’ cooperation, the whole endeavor would be passed off as a testbed for mining manganese nodules from the ocean floor. Since Hughes was known to be eccentric, obsessively secretive and to embrace odd projects (indeed, at this point the 70 year old Hughes was a paranoid recluse living in a palatial Las Vegas hotel suite), the CIA’s hope was that the American media would take it as just one more strange undertaking from Howard Hughes. The manganese nodule mining story ultimately proved sufficiently convincing that several companies took the idea seriously and invested in nodule mining.

With the design, cover story and CIA funding in place, the Sun Shipbuilding and Dry Dock Company in Chester, Pennsylvania started construction. Completed on June 1, 1973, the Explorer cost more than $350 million at the time of her completion (or about 1.67 billion in 2015 dollars) and at 619 feet long and a displacement of over 60,000 tons, the Explorer’s massively reinforced hull was larger than most Second World War battleships and aircraft carriers. Although never formally commissioned into the US Navy (hence on paper she sailed as USNS Hughes Glomar Explorer rather than under the USS designation) she remained government property, the Hughes fiction notwithstanding.

Glomar starboard quarter

As originally built, the Explorer broadly resembled an oil-drilling ship, and indeed much of the Explorer’s technology was related to the offshore oil drilling industry—the K-129 would be ‘grabbed’ by equipment lowered down on the end of what was essentially a three mile long string of 30-foot long sections of pipe similar to that used in oil well drilling. On its own, this tool string massed 4,000 tons. The 2,000 ton forward half of the submarine, half buried in sediment at the ocean bottom, would then be dragged free of the muck and hauled up to the surface, one length of drill pipe at a time.

To enable this, much of the Explorer’s midsection was taken up with equipment custom-designed for the submarine recovery, including two towering gantries and a massive pyramidal derrick system that served as both “drill rig” and as a lifting apparatus with a capacity of 7,000 tons. All of this was stabilized in three dimensions on massive gimbals and a hydraulically operated heave compensator, designed to keep the rig vertical and at the same level despite the motion of the sea. The real secret was a 200-foot long “moon pool,” a dry-dock like space where the ship’s bottom would retract, allowing the K-129 to be hoisted up into the Explorer’s hull for leisurely examination.

Portside aerial oblique view of the Explorer, showing her derrick, docking legs, helipad, and extremely crowded deck!
fig1-1-1 glomar ex - side view plan
The Explorer’s starboard profile, courtesy


fig1-1-2 glomar plan view
A plan view of the Explorer, courtesy
Moon pool interior
Interior of the ‘moon pool,’ courtesy

Along with the Explorer herself came a massive (over 2,000 ton) hydraulically operated grapple, nicknamed Clementine, specially designed to grasp the K-129’s hull. To give some idea of the scale of Clementine, each of the eight claws on Clementine was essentially an assembly of I-beams measuring three feet deep and two feet wide, fabricated from two-inch maraging steel plate, and the whole device massed as much as a Second World War destroyer. There was even a special submersible barge, the HMB-1 (for “Hughes Mining Barge”), built just to make sure Clementine (which was built in California) could be brought aboard the Explorer without being seen, with the pickup happening in shallow water off Catalina Island.

The HMB-1 being towed into position

It is worth noting that by the early 1970s very little deep-water offshore drilling had yet been conducted; most offshore drilling was done in relatively shallow waters (less than 1,000 feet deep) such as the continental shelf off Santa Barbara, California. The only offshore project carried out under similar circumstances was the National Science Foundation’s abortive but still epic “Project Mohole” of 1961, which drilled into the seabed in about 12,000 feet of water in an attempt to reach the Mohorovičić discontinuity, the boundary between the Earth’s crust and mantle. The offshore drilling industry may have benefited from some degree of peace dividend from the project, since the Explorer included a number of cutting-edge technologies, including an mechanical pipe-handling system, an automated stationkeeping system designed to keep the “drill rig” within a forty-foot radius despite the action of wind and sea on the ship’s hull, horizontal thrusters to keep her in position, and her long-baseline positioning system, which became standard equipment for deep sea operations until the advent of GPS decades later.

The actual recovery of the K-129 began on July 4, 1974, and right from the start the operation was as technically demanding and fraught with tension as an Apollo moon shot. Not only did the ship itself have to be kept within a 40-foot radius, but the final positioning of the Clementine grapple had to be exact to within only two feet, which may sound like a lot of wiggle room until you remember that it’s at the bottom of the ocean on the other end of three miles of wobbly drill pipe. Very little information had been available for the project engineers to go on, for example what sort of sediments were on the seabed, so there was considerable uncertainty as to whether the recovery would succeed or not. Several baking-hot days went by in the central Pacific Ocean as one 60-foot length of custom-made drilling pipe after another was fed down into the ocean, all the while under the observation of Soviet spy ships. Tense days later, Clementine was brought into position …

Conceptual image of Clementine being lowered from the Explorer’s moon pool

Well it would hardly be fair for me to just tell the whole story, would it? In any case, much of the documentation behind Project Azorian, including exactly what the CIA recovered, remains classified.

I highly recommend the captivating 2010 documentary Azorian: The Raising of the K-129, which includes extensive interviews with several of the engineers who designed, built, and manned the Explorer during her CIA career. The Historic Naval Ships Association ( also hosts an in-depth technical description of the ship (The Glomar Explorer, Deep Ocean Working Vessel, Technical Description and Specification) on their website at, together with some amazing photographs (some of which were used with gratitude in this blog). This document was prepared in 1975, when Global Marine was trying to drum up other business for the Explorer.

The Azorian story was revealed to the public after a series of leaks to the New York Times in 1975, during a period of extreme scrutiny of the CIA after revelations about other secret undertakings. The affair also produced the notorious “Glomar response,” with the CIA responding to Freedom of Information Act requests from the press with the statement that the government would “neither confirm nor deny” details of Project Azorian based on potential harm to national security.

With her cover blown, and too specialized and expensive to repurpose, the Glomar Explorer herself spent the next twenty years in mothballs at the US Navy’s reserve storage facility at Suisun Bay in California, having sailed on exactly one operational voyage and completed exactly one mission. The HMB-1 was likewise kept around ‘just in case’ for a time before being used as an enclosed space for building prototype stealth ships such as the Sea Shadow. The HMB-1 was subsequently sold to a shipyard for use as a floating dry dock for ship repairs.

Sad explorer
The Explorer during her “mothball” years at Suisun Bay

After twenty years in mothballs, Global Marine Drilling (later part of Transocean) leased the Explorer and gave her a $180 million makeover to convert her into an oil drilling ship, replacing her Project Azorian apparatus with conventional modern drilling equipment. From 1998 through about 2013 she enjoyed a second and much longer career as a deep sea drilling ship before being taken out of service, a victim of declining petroleum prices and competition from on-shore production. Sadly, Transocean announced in April 2015 that the old lady with the mysterious past would be scrapped.

The rebuilt Explorer underway to a drilling project.