Are we there yet? Rebreather technology for recreational divers by Dr Petar Denoble

RF3, Rebreather Forum 3, Karl Shreeves, Richard Pyle, TUMC, The  Underwater Marketing Company, Roz Lunn, Rosemary E Lunn, Neal Pollock, Drew Richardson, Kevin Gurr, Phil Short, Jill Heinerth, Martin Parker, APD, Petar Denoble, Richard Vann, Rebreather Forum 2, Michael Menduno, Yochanan I. Daskalovic, DAN, PADI, AAUS, Douglas Ebersole,

"In the future, you'll simply jump into your car, turn on the Internet, turn on a movie and sit back and relax and turn on the automatic pilot, and the car will drive itself," says Michiko Kaku in his book Physics of the Future. "Unlike a human driver, it doesn't get drunk, it doesn't get distracted and certainly does not have road rage."

Even though driverless cars are not yet commercially available, driving a car is a simple process with all of the complex technology hidden from the user. Today's rebreather technology is a few steps behind, but it may be catching up.

Sixteen years ago diving scientists, manufacturers, divers, training agencies and regulators met for three days at Rebreather Forum 2.0 (RF2.0), in Redondo Beach, Calif., to discuss the future of "sport rebreather diving." At the time, at least one dozen rebreather models had appeared on the market, some of which were there to stay. The market was minuscule, and training opportunities were practically nonexistent. The consumer base consisted of about 100 brave, knowledgeable divers who recognized they could achieve more in their respective fields using rebreathers but at the cost of more work, money and risk than average divers were ready to commit.

RF2.0 reviewed the physiology of rebreather diving and the enabling technology, including the risks and needed enhancements if sport rebreather diving became popular. The findings and recommendations of RF2.0 emphasized the complexity of closed-circuit rebreathers (CCR), a need for technical support and better control of insidious risks including hypoxia, hyperoxia and hypercapnia. Additional safety issues were also noted such as a "caustic cocktail," an unanticipated variation in the partial pressure of nitrogen, thermal considerations and mechanical or electronic failures. Some technological advances were explicitly required, like full-face masks to prevent drowning in case of unconsciousness and an on-board carbon dioxide monitor to prevent carbon dioxide poisoning. Third party pre-marketing testing was advised, but standards were not proposed.

When compared to open-circuit scuba, rebreathers required significant ongoing maintenance and support to function properly; the consensus among the forum attendees was that rebreathers were suited for the technically savvy rather than the average diver. Military divers have successfully managed the risks of using rebreathers with resources not available in sport diving, including the use of a large supporting infrastructure, a high degree of discipline and extensive formal training.

Changing Tides: RF2.0 to RF3

Dr. Richard Pyle describes the experience of a self-taught rebreather diver best: "After my first 10 hours on a rebreather, I was a real expert. Another 40 hours of dive time later, I considered myself a novice. When I had completed about 100 hours of rebreather diving, I realized I was only just a beginner."

He did, however, provide a few survival tips for new rebreather divers:

    1. Know your partial pressure of oxygen (PO2) at all times; do not trust "fail-safe electronics."
    2. Learn, in depth, diving physics and physiology.
    3. Training should emphasize failure detection, manual control and bailout procedures.
    4. Cover your ass (have a back-up).

The experiences and tips of Dr. Pyle and his peers became the basis for development of formal training for technical rebreather divers.

But there were additional challenges for the trainers. According to Karl Shreeves, technical development executive for PADI worldwide, before the training agency could consider the instructional system, it was necessary to determine who the customers would be and how they would use rebreathers. PADI considered rebreather diving a niche not of interest to mainstream recreational divers at the time, but recognized the trend could change at any point. Indeed, a lot has changed; rebreather technology has improved, some training agencies have started offering instruction and the number of users has increased from hundreds to tens of thousands.

The fatalities have also risen accordingly to more than 20 per year, or more than 190 in the sixteen years since RF2.0. Not all of these fatalities were rebreather-specific, but all analyses indicate operator-machine interaction played a major role in it. It's an interaction that must be acknowledged, understood and made as safe as possible. Dietmar Luchtenberg of Europe's Rebreather Advisory Board said, "We can't get rid of safety issues in rebreather diving by [only] increasing technology standards." He emphasized the need and challenge of eliminating the factor of human error to enhance diver safety. After RF2.0, there was also a consensus about the significance of the human factor in the safety of rebreathers; the suggested approach seemed to be to develop a reasonably safe device and shift the residual risk to the users.

The full article is available here at AlertDiverOnline, the magazine for Divers Alert Network

Ambient Pressure Diving support the race to the bottom of the Mariana Trench

We know less about the deepest points on our planet than we do about the surface of Mars. This could all change quite soon because Richard Branson in Oceanic / Deep Flight Explorer and James Cameron in Deepsea Challenge are currently racing to the lowest point in the Mariana Trench; the Challenger Deep. This lies 6.83 miles below the ocean and it's the first extensive scientific exploration in a manned submersible of the deepest spot on Earth.

Two rebreather manufacturers have been quietly involved with this project. Branson has embraced the Poseidon Mark VI as his bailout, whilst Cameron is using Ambient Pressure Diving's technology for life support within the submarine.

James Cameron, Ambient Pressure Diving, APD, rebreather, Deepsea Challenge, Mariana Trench, Richard Branson, Poseidon Poseidon Mark VI, exploration, deep sea diving"Up until today we've had to keep schtum about our involvement on this project", stated Martin Parker.  "We're aware that Cameron has just finished Deep trials in the New Britain Trench.  The Deep Sea Challenge Team have spent the last four weeks off the Coasts of Papua New Guinea and New Britain mounting a series of increasingly deeper dives to prepare for James Cameron's dive to the bottom of the Marina Trench. Surpassing 8,000 metres (actual depth 8,221 metres) for several hours James Cameron is the deepest solo submarine pilot and is in the deepest operational submarine".

Ambient Pressure Diving is responsible for keeping the pilot alive in the submarine - not a small role.

"Our job was to design and manufacturer the complete automatic life support system in the submarine. This includes the primary system and an identical back up system which can be used in a closed circuit mode in an emergency. As you'd expect the life support technology is running smoothly, removing the CO2 and controlling the PO2 in a similar way to the way we do in our standard rebreathers. The main scrubber system is fan driven, powered from the sub...should that power be lost then the pilot can move to the bailout rebreather. In total he's got about 70 hours of life support depending on his work rate. The data is stored on board the Vision system but we also send it live to the on board PAC from where it is transmitted to the surface every 3 mins.

I am very proud to be part of the build team, and exceedingly proud of our in-house engineers and development team here in HelstonAmbient Pressure Diving, Martin Parker, Silent Diving, Rosemary E Lunn, The Underwater Marketing Company, rebreathers who delivered the finished system in four months, from award of contract.  The fact that we used our standard rebreather components and re-packaged them gives us a massive boost in delivery capability and most importantly reliability.

We are in daily contact with the ship, receiving dive download data for cross-checking so that we can support the team out there with advice....these are truly exciting times."

Follow this link and if you look hard enough inside the sub you'll see APD's logo.