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January 2001 Vol. 16, No. 1   RSS Feed for Undercurrent Issues
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Is a Rebreather for You?

Not if you're a casual user

from the January, 2001 issue of Undercurrent   Subscribe Now

If you listen to the advocates, rebreathers are the greatest diving innovation since the regulator: Extended bottom time, reduced decompression, fewer or no bubbles (depending on the type of unit), lighter weight, and improved thermal balance for cold water diving are just some of the claims made by manufacturers. It’s not that rebreathers are new — they were invented in the 1870’s. It’s just that sport diving has evolved to where there is a market for them.

But not much of a market, yet . Draeger U.S. estimates that they have 1,100 - 1,500 units in service in the U.S. Since they dominate the market for semi-closed rebreathers, it’s safe to guess that less than 2000 SCCRBs have been sold in the U.S.

Rebreathers are high-maintenance and tricky to operate, not to mention expensive . They range from $3,500 - $17,500. Furthermore, if you don’t get everything right, a rebreather can kill you. Here’s how the International Association of Nitrox and Technical Divers (IANTD) compares the hazards of rebreathers. “Rebreathers have certain specific complexities which introduce forms the light, fluffed my pillow, and tried to fall asleep. You can order “The Last Dive” by going to Undercurrent, scrolling down to Editor’s Book Picks, and clicking on the photo. That way you’ll get the best price of ($20 plus shipping) and a percentage of the sale will go to support the Coral Reef Alliance. (“The Last Dive,” published October 2000, by Harper Collins, is available in local bookstores for $25). of risk not experienced by scuba divers ... On scuba, if a diver can breathe and is not outside wellestablished depth limits, the breathing gas is going to be life-sustaining (assuming the cylinder was filled properly). If there is a problem with an open-circuit system, the problem is usually very self-evident to the diver, so the diver at least is aware of the problem and can take steps toward a solution.

“With rebreathers, however, the breathing gas may be dynamic, and thus the oxygen concentration may drift out of life-sustaining range within the course of a single dive. Under certain circumstances, especially during high exertion and/or during an ascent, the oxygen concentration in a semi-closed rebreather could drop to dangerously low levels.”

Semi-closed rebreathers (SCCRBs) such as Dräger's Dolphin, use a compressed-gas supply and a regulator, and discharge exhaust gases (including some oxygen) with each breath. At proper flow rates, they produce bubbles only after three or four breaths, and those bubbles are vented behind the diver’s head.

Even trickier are closed-circuit rebreathers (CCRBs) such as the PRISM Topaz, which recirculate the breathing gases and employ an electronic sensor to replace depleted oxygen. The inherent weakness of these models, according to IANTD, “is the reliance on electronics to control the oxygen concentration in the breathing loop.”

While in recent years there have been more than a dozen deaths of divers using rebreathers, DAN’s Joel Dovenberger is aware of only three in the U.S. The most recent occurred this August in the kelp beds off La Jolla, California. Popular diver and web page designer Ron Fuller, 51, was found in 50 feet of water, directly off La Jolla Shores. He had gone diving alone and was using a FROG rebreather made from a kit, which had malfunctioned two weeks previously, forcing Fuller to abort a dive on the Canadian destroyer Yukon, which was recently sunk off Mission Beach.

Two other experienced divers died this spring in Europe while using Buddy Inspiration CCRBs. There have been eight deaths since 1998 involving the Inspiration. According to DIVE magazine, published in the UK, about 1,000 units have been sold — that suggests an astronomical death rate.

Should you try one?

Rebreather training and rental are in vogue. But, the rebreather industry is so new that many bugs remain, both in unit designs and training. Several agencies offer SCCRB training as do some manufacturers. For instance, Steam Machines, which sells the Prism Topaz CCRB, offers training, either at the factory or through a handful of specially-trained TDI or NAUI instructors.

Because you’re taking your life in your hands each time you strap on a rebreather, don’t look for training shortcuts. Expect several hours of class time, followed by at least one confined water session and three open-water checkout dives. That’s the curriculum followed by PADI (

NAUI’s ( training is more comprehensive, requiring 16 hours in the classroom, five hours in confined dives, plus six open-water dives. Technical Diving International (, headed by diving maverick Bret Gilliam, requires six briefing hours and four open-water dives for at least 100 cumulative minutes. Certification ranges from $300 to $500 for semi-closed units and $1,500 to $2,000 for closed circuit models.

You’re taking your life in
your hands each time
you strap on a
rebreather ... don’t look
for training shortcuts.

Some resorts and live-aboards offer You’re taking your life in your hands each time you strap on a rebreather ... don’t look for training shortcuts. rebreather training. Check Sunset House (800/854 - 4767) or Dive Tech (345/949 - 1700) on Grand Cayman, and Dive House (011-52-987-21953) on Cozumel.

Rebreather training is offered on many Aggressor liveaboards (800-348- 2628) and on the Undersea Hunter and Sea Hunter (800/203-2120) operating in Costa Rica. The courses are usually given on Dräger Dolphin or older Atlantis semi-closed units, which are the most widely available for either purchase or rental. These may not be as comprehensive as those offered through land-based instructors so before signing up, pin down as many details as possible. For instance, on the Aggressor Fleet, different instructors offer different certifications. Be sure you’re comfortable with the level and extent of classroom and in-water work. Do some preparation, such as perusing the Dräger owners manual on their website:

A dive rebreather “experience,” a high tech version of a resort course introduction, is becoming widely available. But it’s inadequate for many people, who will need more than a short lecture and one dive to get used to the uniqueness of rebreathers.

Training at Sea

Chuck Tribolet, an Undercurrent reader from Morgan Hill, CA, got a TDI certification on the Sea Hunter and liked it well enough to buy his own Dräger Dolphin. An underwater photographer, he considers himself a techie, so he wasn’t put off by the TDI training materials, which do not translate tech jargon into lay terms. Chuck points out that the equipment requires a lot more setup and care between dives than traditional scuba. When underwater, the major difference is being aware of exhaust bubbles every third or fourth breath; that’s confirmation that the system is delivering gas at the desired 02 levels.

Reader Karen Cousins of Falls Church, VA, advocates getting certified before a trip, as she and her husband Bill did before shipping out on the Undersea Hunter to Cocos Island. “Once you’re on a liveaboard,” she points out, “you could become too ill, too travel-weary or too distracted to give the training the attention it deserves.” Karen and her husband Bill took private lessons on the Dräger Dolphin as well as the smaller Dräger Ray (both SCCRBs), which Karen felt gave them a broader education than if they’d just been certified on a single unit.

Karen thought the training conducted aboard the Undersea Hunter was more rushed and less extensive than hers had been. Classroom sessions were held in the salon during the rocky 36-hour passage to Cocos, with people passing through, others getting sick just outside, and lots of other disruptions. Students didn’t appear to receive as much documentation, either.

One diver on her trip took the rebreather intro, a 10-minute orientation and a single dive. Karen says that in such a limited intro, “Ignorance is bliss, while the full training scares the crap out of you.” She points out the need for a thorough indoctrination: “The system is unforgiving. It’s either working or it’s not.” Checking her own gear after each dive increased her confidence level, as she became more familiar with the equipment and its operation.

Although Karen initially hated the increased breathing resistance of rebreathers, she eventually adapted, and came to love the silence. Even the familiar scuba regulator rasp was missing. Rolling into the water at Cocos with a rebreather caused “immediate sensory overload” as Karen encountered hundreds of hammerheads and other sharks, freeswimming octopuses, and eels curling around divers’ legs ... even a sailfish.

“On scuba,” as she describes it, “you’re swimming with the fish. On a rebreather, it’s more like just being with them.”

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