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Diving Deep into Danger

National Hyperbaric Centre
Student divers training in a saturation complex at the National Hyperbaric Centre, Aberdeen, Scotland

Divers work not for oil companies but for private contractors, which range from smaller, independent operations to larger, publicly traded companies like Cal Dive, Helix Energy Solutions, and Oceaneering. These larger contractors have their own training processes for saturation divers that are often more rigorous than what is mandated by federal law. There is a general touchiness in the industry about safety, especially since the BP Deepwater Horizon tragedy. Shell or ExxonMobil is unlikely to hire a contractor with a reputation for carelessness.

Most offshore divers aspire to work saturation jobs (“Sat is where it’s at,” says Newsum), but after graduating diving school and passing an extensive physical, a diver must begin as a “tender,” or apprentice diver. A tender will serve on the support staff for deeper divers, and work at depths as shallow as four feet of water. Often a tender will assist on jobs involving oil pipelines, which tend to be buried four to six feet below the mud line in order to avoid contact with ships or marine life. A tender might be called upon to bury a repaired pipe, using hand jets to displace the bottom so that the pipe will sink belowground. Or he might excavate a pipe, in preparation for a more experienced diver to repair it. An apprentice makes about $40,000 a year.

The deeper you dive, the more you get paid. In his second or third year an apprentice may be promoted, or “broken out,” to a full-time diver. His salary will increase to between $60,000 and $75,000. He will start as an “air diver,” diving as deep as 120 feet while breathing regular air. Jobs at this depth might include retrieving tools from the worksite, or cutting and retrieving the polypropylene cord that runs between the surface vessel and the underwater worksite. Next the diver will be assigned to more complex jobs below a hundred feet, for which he must breathe mixed gas in order to avoid suffering the effects of nitrogen narcosis while working with heavy machinery. A full-time mixed-gas diver can earn more than $100,000 a year. He will perform jobs at ever greater depths, with higher degrees of technical difficulty, until his diving supervisor deems him ready to graduate to saturation diving. Sat divers can make $200,000 a year. Sat’s where it’s at.

A saturation diving complex looks like a small space station. It comes in different sizes, accommodating six to twenty-four divers. A typical complex, which sits on the deck of a ship or an oil rig, has four main components. The first is the living chamber, which resembles a train’s sleeper car, or the berth of a submarine, and has double-decker cots with fire-retardant mattresses and a sitting area with a television screen. (Larger systems have two or even four separate living pods.) A camera—often referred to as “big brother”—peers through a porthole, observing the divers. Other portholes, covered with plexiglass, allow the marooned divers to glimpse the outside world.

By crawling through a short tube from the living chamber you reach the transfer lock, a small capsule that contains a toilet, a small sink, and a showerhead. At the top of this chamber is a hatch that leads to the diving bell, which can take the shape of an amphora, an orb, or a squat cylinder. The diving bell is encased within an exoskeleton of pipes, which are responsible for lifting it to and from the complex. Another portal leads to the hyperbaric rescue chamber, the equivalent of a lifeboat, which has enough breathing mixture to last the crew for three days. On newer, more technologically sophisticated ships, the saturation complex is built into the body of the vessel, below-decks. On these models the diving bell drops into the water through an opening in the bottom of the ship, called a moon pool.

Once the divers are sealed inside the saturation complex, the air pressure is increased until it matches the pressure at the job’s working depth—this generally takes about a day. The breathing mixture inside the complex is also adjusted accordingly—the deeper the job, the more helium will be added to the breathing mixture. (Helium, besides allowing divers to avoid the risk of nitrogen narcosis, is easier to breathe under pressure because of its low density; it is also more quickly flushed from the organs and tissues than heavier gases.) This causes the divers to sound like Donald Duck, or children who have inhaled helium from balloons at a birthday party. But a diver inside the system doesn’t always realize that he sounds like Donald Duck, because the other members of the crew also sound like Donald Duck.

This condition is known as “helium ear.” The diver must often be reminded to enunciate his words when he speaks through the intercom to the supervisors and life support technicians who monitor him from outside the complex. Saturation systems often come equipped with a Helium Speech Unscrambler, a device that slows down the speed of the divers’ voices. One company that manufactures these devices boasts of their ability to correct a diver’s “raw helium speech to normal intelligible voice levels.”

Food is delivered to the crew through the medical lock, a small passageway that serves as the vessel’s mouth. The med-lock is clamped on either end. Before the divers retrieve their meal, it must be “blown down” to the same pressure as the rest of the complex. Changes in pressure affect one’s sense of smell, so meals tend to taste bland. Some types of food, particularly those with air bubbles, do not withstand compression. Carbonated beverages turn flat. Rice Krispies collapse. Pancakes wrinkle up. Certain materials break down as well; Styrofoam, for instance, will shrink, or implode.

All jobs at a depth of three hundred feet or deeper are required by law to use a saturation system, but it often makes financial sense to use one at shallower depths for more involved jobs. A diver using mixed gas cannot remain deep for a long period of time, for these dives require many hours of decompression and recovery. Saturation divers, on the other hand, can work full eight-hour shifts, and must only undergo decompression once, when it is time to leave the complex. Saturation gas diving can be cheaper, even at lesser depths, for the helium gas that divers inhale, which is expensive, is not wasted but recycled. In a saturation system, exhaled gas is captured by a reclaim system, which sends it through an apparatus that “scrubs” the gas, remixes it with a fresh helium and oxygen mixture, and returns it to the breathing tank. So both the air and the divers are recycled.

Saturation diving also allows work to continue unceasingly until the job is finished. Divers tend to work in pairs, as most diving bells hold two people—a crew of three pairs of men can work without interruption in consecutive eight-hour shifts, making possible twenty-four hours of continuous work. The bell functions like an elevator with two stops—the underwater work site and the saturation complex. Divers can look out of a porthole and watch the light dim as they sink; often by the time the divers reach their working depth—it can take an hour—the water is pitch black. The bell has external lighting panels that function like headlights; these are used to illuminate the working area, which might be an old platform that needs to be dismantled, or a busted wellhead.

The bell is connected to the saturation complex by a large cord that contains within it smaller tubes, which in turn contain breathing gases, electricity, and fiber-optic lines for communication. The divers’ lives depend on this cord, which is called the “umbilical.” Smaller umbilical cords connect the divers’ breathing suits to the bell. There is a video camera in each diver’s helmet, and a microphone that allows the diver to communicate with his supervisor. (Supervisors tend to be former saturation divers who have aged out of the job.) Because the water at these depths is close to, or even below, freezing, a tube pumps warm water, collected from the surface of the ocean, into the diving suit. This turns the suit into a personal hot tub. There is an oft-repeated cautionary tale, likely apocryphal, about a diver whose air hose vacuumed up a jellyfish from the ocean surface and pumped it down into his suit, the angry jellyfish getting trapped in the crack of his ass.

When the job is finished, the divers can’t simply leave the complex. They must first decompress. The formula is one day of decompression for every hundred feet of depth, plus an extra day, which means that a crew saturated at a depth of a thousand feet must wait eleven days before they can leave. (Divers rarely work below a thousand feet, the point at which they become susceptible to high-pressure nervous syndrome, which can result in nausea, vomiting, tremors, and neurological damage.) During the decompression period, the pressure in the saturation complex is reduced gradually, with many rests along the way, so that the body doesn’t undergo shock. The breathing mixture is changed as well, until, by the final day, the divers are breathing normal air. Upon exiting the saturation complex, they are given a full physical examination and kept under observation for twenty-four hours. They must wait seventy-two hours before they can board an airplane.

If a saturation crew is already in the Gulf, their contractor will look to attach them to another job if possible. It’s always cheaper for an oil company to hire a crew that is already at sea rather than fly a new crew out from the mainland. So with any luck, the crew may be resealed inside a saturation chamber within days.

Commercial diving remains a dangerous job, but not for the reasons that haunted early experimenters like Hannes Keller. Whether saturation diving has long-term repercussions for human health remains a subject of cantankerous debate. Some scientific studies have shown moderate impairment in spatial memory, vigilance, and reaction time among those who have worked as saturation divers for more than three and a half years. One such study was cited by the government of Norway in 2000, when it decided to award several million dollars in workers’ compensation payments to sat divers who had worked in the North Sea oil industry between 1965 and 1990.2 More than a decade later, there is still no scientific consensus on the residual health effects of saturation diving.

The work itself, however, is extremely dangerous. A CDC report in 1998 estimated that the occupational fatality rate for commercial divers was forty times the national average for all workers, at an annual rate of 180 deaths per 100,000 employed divers. These numbers have declined slightly in the last decade, in which, according to the US Coast Guard, nineteen commercial divers have died offshore. An additional twenty-four workers died diving inshore, which involves work in lakes, rivers, or coastal harbors, and relies primarily on scuba diving. That comes out to an annual fatality rate of approximately one per every thousand divers, or twenty-eight times the national average.

  1. 2

    See Longterm Health Effects of Diving: An International Consensus Conference, edited by Arvid Hope, Tjostoly Lund, David H. Elliott, Michael J. Halsey, and Helge Wiig (Bergen: Norwegian Underwater Technology Center, 1994), p. 391. 

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