Tech Divers going to great depths

PULLEY RIDGE — Just as American Indians led Lewis and Clark and other explorers across the New World several centuries ago, a new breed of scouts is guiding explorers into uncharted territory. This terrain is several hundred feet below the sea and the explorers are some of the world's leading scientists.

These new scouts, actually technical divers trained to dive to depths of more than 300 feet, face challenges more like astronauts than their counterparts of the early 1700s. Despite the technological advances, they are still limited in the time they can spend at the bottom of the sea.

On one recent scientific exploration that was the first time divers had visited a deep reef, a crew of technical divers had less than a half hour to collect sponges, green leafy algae and various plant and animal life. Grabbing the wrong regulator or pushing the wrong button could mean pumping the wrong gas into your system at the wrong time, causing the diver to become unconscious or even die.

Recently, Key West naturalist diver and Explorers Club fellow Tim Taylor and Mote Marine Laboratory staff scientist Jim Culter led a hand-picked group of highly experienced "tech divers" to serve as scouts and sample collectors on Pulley Ridge, a reef 275 below the ocean surface and more than 150 miles west of Fort Jefferson in the Dry Tortugas.

Scientists called the days of research a monumental success and credit the tech divers with much of that achievement, citing their ability to retrieve samples where submersible and remote operating vessels couldn't.

The divers worked in conjunction with scientists exploring the bottom in a $1.5 million submersible research vessel and a remote control vessel. Deep Marine Technology (DMT) of Houston, Texas, loaned the submersible to the research team. The one-person, one-atmosphere "Deep Worker" submersible is fitted with cameras and devices that allow the scientists to grab samples and place them in a small plastic basket. The Deep Worker was invented and built by Phil Nuytten, of Nuytco Research in British Columbia, Canada, said Wes Tunnell, a marine biologist and associate director of the Texas-based Harte Research Institute.

Florida Keys National Marine Sanctuary Superintendent Billy Causey was so impressed with the tech divers and technology that he has begun to look at developing a long range plan to infuse more technology into sanctuary projects.

"This is really exciting stuff," Causey said. "These technical divers are scientists. They are explorers and they are going to tell others. They have a real passion for the sea and you can't get that kind of passion for it unless you are there."

Taylor, operator of the Key West-based research vessel Tiburon, said his team's work represents "the future of underwater research and exploration."

"This type of diving allows more opportunities for research at depths not possible before," Taylor said.

The divers, Explorers Under the Gulf (EUG), have descended to some of the most challenging underwater areas for divers in South Florida, including traversing deep into a freshwater cavern more than 250 feet below the Gulf of Mexico called the Mega Dome. The divers' only payment for their hard work on Pulley Ridge was the gratitude of scientists and a chance to dive an area that has never been dived on before in recorded history.

"These guys are dedicated disciplined professionals. It takes a great deal of training and experience to work up to this point. We had some real objectives for them and they performed perfectly. We have been waiting years for this advance in diving to be applied to science," Culter said.

Culter spent several weeks training the divers on collection techniques and what to look for under the sea. That training was easy compared to the years of study, both above and below the water, they endured to become tech divers. In this kind of diving, experience is the key factor.

The technical diving world is evolving from open circuit divers, who take a breath and when it is exhaled it floats away to he top of the ocean, to divers using a closed circuit rebreather, a device that is revolutionizing the diving world. These rebreather divers use a fraction of the expensive gas allowing the support vessels to extend their range and capabilities.

The technical divers on Pulley Ridge were divided into two categories, depending on what technology they were using. Three of the Tiburon imaging team were using rebreathers and eight divers used the more traditional open circuit.

"I believe within the next five years [rebreathers] will be the only thing used at these depths," Taylor said. "They are the future."

Taylor has used them in three Explorers Club Flag expeditions this year — a shark behavior study and two deep coral studies.

Like astronauts, the technical divers must mix different forms of gas, like oxygen, helium and nitrogen. These explorers are pioneering advanced technology similar to what NASA uses to keep its astronauts breathing and maximizing the gas resources available.

Helium is used to eliminate or cut down nitrogen from a diver breathing gas. Nitrogen at depth has a narcotic affect on the diver, while helium does not. Helium is a much lighter gas and brings with it its own set of issues.

It comes out of solution faster, so divers must start their decompression at greater depths. It also has poor thermal properties which equate to making the diver colder sooner. At the depths of Pulley Ridge, the crew decided it was best to use nitrogen and helium. The nitrogen helps buffer the helium, making an easier, more comfortable dive.

The rebreather is a backpack-like device similar to a standard diving buoyancy control apparatus. Instead of one or two large bulky aluminum or steel tanks, the rebreather houses two much smaller tanks and what is known as a "scrubber" that absorbs carbon dioxide exhaled by divers in order for the diver to not be asphyxiated.

The diver reuses the gas and has a small amount of oxygen replaced each breathing cycle. The "closed-system," as it's known, has built-in computers allowing the diver to program depths and times and what mixture of gas is needed.

The rebreather divers still bring two small bail-out tanks, under each arm, in case of a system failure. But the entire week at Pulley Ridge they never needed them. Breathing recycled air after it's cleaned allows divers to save money on buying and mixing large tanks and extending the range of boats like the Tiburon.

Taylor has been working with a rebreather company, Silent Diving Systems, on educating scientists and explorers on rebreathers and their use.

"These are not just for deep diving," Taylor said. "We are applying these with many of our researchers in animal studies as well as mid-range coral surveys. The extended range and silent operations make them ideal for photographers and behaviorists."

The eight other open circuit divers strapped two large tanks to their backs. The tanks are connected to two first-stage redundant regulators and an extra large buoyancy compensator. The divers had two large staging tanks on their sides used to get to and from the bottom and decompress at shallow depths. The divers used state of the art dive computers that tracked their entire dive profile.

These computers help them to know when to change gases and can be recalibrated underwater. The open circuit divers consumed several thousand dollars in gases alone, while the rebreather divers gasses cost less than $100.

tohara@keysnews.com