Heavy Breathing about Rebreathers

Conventional scuba is basic -- pump a tank full of air, breathe it through a regulator, absorb a small amount of the oxygen, and exhale what's left out of the regulator. Simple, but inefficient.

The idea behind rebreathers is greater efficiency. Instead of just exhausting the air after breathing, run it by again and extract more of the oxygen. Efficient, but not so simple.

Rebreathing can be achieved by other means (for a detailed description of closed-circuit and semiclosed rebreathers, see Undercurrent, May 1996), but the results are the same -- longer bottom times (in most cases) and no loud bubbles to scare fish.

I can read about rebreathers and their advantages in every dive publication. I can even pay a price, take a course, and test dive a rebreather. But can I buy a rebreather? Is the technogy here now for rebreather sport diving? After returning from this year's Diving Equipment and Marketing Show (DEMA) in Orlando, where rebreathers were a major hype, I asked these questions of a genuine technical diving guru, aquaCORPS and tek.Conference founder Michael Menduno (a.k.a. "M2"). Here's his reply.

The problem of designing a working rebreather is evidently a lot harder than most manufacturers had anticipated. Out of the ten vendors at the 1997 DEMA show, only two companies appeared to be actually delivering product -- Dräger and Grand Bleu. That didn't stop the others from pushing prototypes while promising delivery dates later this year.

The Here and Now

Grand Bleu's entry into the U.S. rebreather market , the Fieno, was introduced to DEMA this year with a flourish. A squad of diminutive "Fieno Girls," clad in soft-white schoolgirl blouses, matching pumps, Fieno rebreathers, and hip-high cheerleader skirts an inch too short to hide their shiny blue underwear, patrolled the showroom floor, leading would-be takers back to a 30-foot-high stack of Japanese rebreathers. The sign at the base of the pyramid read, "KEEP YOUR HANDS OFF. PLEASE." Whether the warning extended to the company's marketing provocateurs was a source of ongoing speculation at the show.

According to company literature, the Nissan affiliate plans to have 600 units available for dealer sales and lease from its U.S. sales office in San Diego this year. Introduced to Japanese consumers in 1995, the Fieno-S, a $2,800, constant-mass-flow, semiclosed rebreather, was designed for 40-minute, 30-metermax, no-stop "relaxation diving." An appropriate designation; with a maximum oxygen flow of only 2.0 liters per minute, this small, 4.5-liter counterlung is more suitable for Asian lungs. It would not be difficult for a hard-swimming diver to outbreathe the system and go hypoxic, one of the principal risks of systems of this type.

Earlier last year, concerns over hypoxia led German rebreather manufacturer Dräger, which supplies semiclosed rebreathers to the U.S. and other militaries of the world, to quietly boost the flow rates on its consumer entry, Atlantis I. This nofrills, semiclosed Nitrox rebreather relies on an automatic bypass system to feed fresh, oxygen-rich gas into the system under heavy workloads. Unleashed on Europe in early 1995, it was designed specifically for nature-loving recreational divers at a time when U.S. vendors were busy fawning over high-end tekkies.

I caught up with Dräger's point man Christian Schult, who was eyeing some of the equipment displayed by a Fieno Girl. He confessed to me that they were glad to see that someone else had actually entered the market, too: "It made us a little nervous being the only ones out there."

According to their marketing manager Jürgen Tillman, since its 1995 introduction Dräger has shipped about 850 units worldwide through an international marketing agreement with Uwatec SA, but not before cutting retail prices nearly in half, from $6,500 to $3,500, presumably in response to consumer apathy, as there was no competition.

Quantitatively, this represents a big leap for rebreather technology, which until now has been limited to small volumes and tight control at the hands of military users. To put things into perspective, the two largest rebreather users on the planet, the British Royal and U.S. Navies, have a combined total of only about 240 mixed-gas units in service (excluding pureoxygen systems) out of an inventory of approximately 600. According to military insiders, the keys to their success are the large support infrastructure and rigorous protocol, factors that are absent in sport diving circles.

The Maybe Coming Soon

Cis-Lunar Labs, Cochran Undersea Technology, and Brownie's Third Lung each displayed a single high-end preproduction system that looked remarkably like the same units presented at tek and DEMA last year. Those systems were supposed to have been ready for delivery in early 1996, but I haven't seen a production model yet.

In October, Cis-Lunar CEO Richard Nordstrom told me that his company planned to launch its $15,000, closed-circuit MK-5 system in a big way this DEMA. The MK-5 is the next generation of the system that caver-inventor Bill Stone designed to explore the Huatla Peninsula in Central Mexico. Nordstrom added that Cis-Lunar wasn't going to promote the unit until it was ready, but the lone beta unit nestling in a corner of the DiveComm booth told the story.

Cochran also reportedly wanted to launch their new system at DEMA but suffered key personnel losses two months before the show, including British rebreather entrepreneur-designer Peter Readey. Readey, who teamed up with the company in 1995, had been largely responsible for Cochran's rebreather effort -- an innovative, electronically controlled, closed-circuit system named Prism 2.0 with a targeted $8,000 price tag. The two reportedly parted company amicably, with Readey retaining the name Prism for his new venture, Steam Machines. At the show, Readey and partner Bill Thackeray were working off a table top hidden among Caribbean tour operators. The company plans to train interested users and lease (not sell) units from its growing fleet of MK-15.5 closed-circuit systems and Readey's new creations.

Last year, rebreather designer Jack Kellon teamed up with Ft. Lauderdale manufacturer Brownie's Third Lung, brought his machine that had been developed under several previous incarnations, and renamed his $15,000, semiclosed system Halcyon. Although thxis rebreather has been nominally available since 1995, as of this April it has not been fully tested.

Bio-Marine Instruments and Undersea Technology were both slated to introduce their electronically controlled, closedcircuit systems in the fall of 1996. As of DEMA, neither company was ready to ship. Believers who had put down deposits on Bio-Marine Instruments' CCR 500 were relieved to see the company at the show, albeit with only one prototype. The $5,000 unit is a scaled-down version of the USN MK-15/16 series of mixed-gas rebreathers designed more than a decade ago by the original manufacturer, Bio-Marine Industries, before Carleton Technologies wrestled away the Navy contract in 1989.

Undersea Technologies is an affiliate of UK-based Carmellon Research, which entered into an agreement with California manufacturer Oceanic in 1992 to jointly develop a family of rebreathers known as Phibian. Last year the two companies decided to sue each other, and a federal court granted Carmellon the exclusive rights to use and market the technology, while preventing Oceanic from entering the market until 1999. Though it was scheduled for release last fall, software and other design problems have kept Undersea's $15,000 UT 240 system off the market. The company was displaying several prototypes, including its $7,500 UT 180 at this year's show.

New to the circuit were the Association of Underwater Rebreather Apparatuses (AURA) of Seattle, with a $4,900 CCR 2000 closed-circuit system, and Marine Technology Development Inc., which displayed two closed-circuit designs priced at near $5,000, the Frog and the Gator. According to the Marine Tech's literature, the Frog and Gator systems maintain a constant percentage of oxygen, just like open-circuit scuba, rather than the constant oxygen partial pressure common to closedcircuit technology.

Is the Technology Sound? Because of their complexity, there is no way to determine how units will perform in the field without thorough human and machine testing, which can cost upwards of $25,000 for a basic test series, according to Dr. Ed Thalmann of Duke University.

"All the units I saw at the show are still on the edge," said Divematics closed-circuit design veteran Tracy Robinette, who has done work for most of the rebreather vendors at the show. "Manufacturers have not had enough time or testing to verify the performance of any of these units."

Other than Dräger, none of the manufacturers displaying units at the show have finished testing, so manufacturers' claims remain just that -- claims. My favorite claim was made by AURA, another company entering the rebreather field, with respect to its new CCR 2000. The color-copied brochure said, "Unit functions safely to 2,000 feet." I don't think so.

Whether or not sport makers will be able to match the military's safety record while pumping out rebreathers in volume remains a matter of some concern. USN has had four incidents in 16,000 hours on the MK-16 mixed-gas rebreather; one of them resulted in a fatality. Retired Navy Captain Ed Thalmann, who ran the Navy Experimental Diving Unit's lifesupport testing program for 15 years, framed the technological challenge facing the sport diving industry this way: "A scuba regulator is the steam engine of diving gear. It's been around for a long time and it's incredibly reliable. By comparison, a rebreather is like a space shuttle. The problems are not academic. If you don't know what you're doing, then you'll wind up dead."

A diver since 1976, Menduno coined the term "technical diving." He is a freelance writer and edits tec.asia magazine from his base in Key West. You can e-mail him at m2aqua@worldnet.att.net