Tech & Kit

Navy Experimental Dive Unit: Testing Pools, Chambers Put Humans, Gear to the Test

SAN DIEGO, CA (PO2 Robert Sanchez) – Several hours into a six or seven hour experiment, a Navy test subject clad in a prototype dive suit floats near the bottom as he communicates with a topside team of engineers, physiologists and technicians at the Navy Experimental Diving Unit, Naval Surface Warfare Center here, and it seems they’ll have a far more complex puzzle to solve.

Navy Master Diver Ryan Langley, NEDU operations department master diver, said he and his team are charged to test human biometrics, glean vital data points, and assess dive gear for form, fit and function before it’s sent out for fleet use.

“We want to have a controlled environment here before we put everyone in the unforgiving mercy of the ocean,” Langley said. “It’s a safe environment, it’s a quick exit and we have a treatment facility right here so if something does come about, we can treat it immediately.”
Langley said the operations team can adjust the water from a glacial 35 degrees Fahrenheit to a boiling 105 degrees Fahrenheit.
Chilling Out

As some of the recreational objects beneath the surface might suggest, test subjects submerged for six-to-seven hours pass the time to beat boredom and enjoy creature comforts while the NEDU team scrutinizes their core temperature and vital signs, as well as dive gear that’s passed the review phase.

“We have some things down there to keep them busy, some underwater football, we also have a [movie] projector … and they can hear through a transducer underwater,” Langley said. “So right now, I don’t know if you can hear it, but they’re actually watching ‘Elf.’”

Other apparatus includes a horizontal exercise bike with RPM monitoring equipment to simulate diver output on the bottom during a working dive, Langley said.

Still, even the sharpest divers can face daunting conditions during experiments.

“When you’re at the bottom of this pool for a very extended period of time, your mind does start to play tricks on you, and you get very bored,” Langley said. “Sometimes the elements may get to you, so you have that constant thing in your head, ‘Do I want to get out now? Do I want to stay down here? What will everyone else think about me?’” But, he asserts, “having that perseverance to get through a dive, even though it’s not the most fun or comfortable thing at the time, plays a lot into what we do here.”

Under Pressure

As a 12-foot pool cannot be pressurized, the NEDU team sometimes conducts saturation dive tests to analyze deeper dive conditions while stanching decompression sickness in their experiment participants.

That’s when the behemoth, five-chamber, self-contained, temperature and pressure controlled ocean simulation facility comes into play.
Navy Diver Senior Chief Petty Officer Eric Wilson, NEDU command master diver, said the OSF is the most complex and largest saturation facility in the Defense Department’s inventory. It was developed in the late 1960s and installed at the NEDU in the early 1970s before being commissioned in 1975.

“Our depth capability is 2,250 feet, we did saturation dives up to 1,800 feet in 1979, and we continue to do saturation, cutting-edge diving for the Navy all the way to today,” Wilson said.

Once the highly-seasoned divers arrive to the NEDU, they’ll spend a good 6-12 months training together in preparation for extended time in very close quarters.

“The qualification process is probably like no other in the sense that we do saturation diving [and] you are sometimes in the chamber for 5, 6, 10 or 12 days,” Wilson said.

To mitigate that, Wilson said the NEDU team builds a “sat” team in which the test subjects physically train together, eat together, and live closely during a work-up cycle ranging from 1-3 weeks, depending on the dive series.
An institutional review board proposes a protocol based on a fleet requirement to decide whether a test calls for human subject research, equipment research, biomedical research or some combination thereof.

“It comes down to a roundtable decision,” Wilson said. “But the bigger picture is we are putting a stamp as a Navy Experimental Diving Unit for a piece of gear that’s going to be used out in the fleet by other Navy divers, Navy Seals, explosive ordnance disposal techs, so safety is our number one concern.”

In Touch With Technology

Safety, he said, has been at the centerpiece of the NEDU’s modernization, stemming from its test dive history in the late 1930s to current state-of-the-art touch-screen consoles in line with “Force of the Future” technology.

“The old antiquated push-button is gone, so to the younger generation, it is cool because it’s no different than your iPhone,” Wilson said of the control room computers connected to the OSF. “I can drive this chamber to 2,250 feet of saltwater by a push of a button — I can control the temperature inside, the humidity, compression, decompression as well as different gas shifts … that’s the way we mitigate for the sat team inside to ensure everybody stays safe.”

The ocean simulation facility, Wilson said, “has a massive infrastructure electrically and mechanically, and the support equipment that goes with it would blow your mind.”

The saturation dive “presses” the team into 40 feet and establishes an atmosphere, at which time test controllers have about 60 minutes to abort a dive and decompress based on a standard Navy gas table or air table. Once they’ve committed to the dive, they press into storage depth, which ranges from 100-1,000 feet of saltwater, Wilson explained.

“Within 12-72 hours, the body is saturated,” he said. “If we left bottom, I am outside of my normal approved tables to just come straight to the surface, so I would bend [cause decompression sickness in] somebody.”

When the body is saturated and can no longer take on anymore nitrogen, Wilson said he and his team use different gasses to purge those bubbles out of the test subjects and create an atmosphere where they can stay on the bottom for up to 30 days in the certified chamber.
“Our golden rule in the saturation world is a day for every 100 feet, plus one,” Wilson said. “So if we were doing a 1,000 foot dive, it would take me 11 days to get to the surface — it’s a lot of movies [to watch].”

‘Camping With Buddies’

Wilson described the unique but space-efficient chamber conditions as a lot like “camping with buddies,” adding that the middle chambers are set up set up as closely as possible like a conventional living space, complete with bunks, video monitors, a wide array of movies, and cots to relax.
And to move things from the outside world to the sat team, each of the chambers has a “med lock,” to transfer medicine, food, coffee or whatever they need. “The sat team gets pretty spoiled, as they should,” Wilson said.  Still, Wilson acknowledged dive team members will lose some elements of normalcy, in the interest of safety.

“It’s important as dive watch officers and supervisors to be able to monitor that team 24-7; whether asleep, diving or awake so the lack of privacy kind of goes out the window sometimes,” he said. “We do have showers and toilets inside for the team, but we have to have cameras on — it’s just something you get used to.”

At the end of the day for the 130-member NEDU team that’s comprised of about 75-percent military, the mission statement is simple, Wilson said.

“We partner with the warfighter on a daily basis to improve equipment and procedures, not just in the Navy, not just in the DoD, but across the worldwide diving community,” he said. “We’ve all been out in the fleet and used the gear and the procedures that have been tested and a lot of us come back.”

Sharing Wilson’s sentiment is Navy Diver Petty Officer 1st Class Greg Early, NEDU leading petty officer for testing and evaluation, who directs and conducts unmanned recompression tests to evaluate equipment performance or forensically study equipment failures.

“Even though the technology changes, the most-important part is making sure the equipment is safe for the diver to use,” Early said. “When the technology changes, we still have to center the testing around the person using it.”

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