Sport Rebreathers – Past, Present and Future Pt 2

Last month SIMON PRIDMORE looked at the history of sport rebreathers and explained why they failed to catch on in

archive – TrainingSport Rebreathers – Past, Present and Future Pt 2

Last month SIMON PRIDMORE looked at the history of sport rebreathers and explained why they failed to catch on in mainstream diving in the 1990s. In the second decade of the 21st century, a series of developments took place that would push rebreathers back into the mainstream limelight

FIRST OF ALL, A LITTLE background: for any new technology to make significant headway, first the market at which the technology is aimed needs to be prepared to accept it. It is useful here to go back a few years, and draw a parallel with what happened with nitrox.
Before 1995, the only training agencies teaching divers to use nitrox were relatively small boutique outfits such as IANTD and ANDI, and very few dive-centres worldwide offered nitrox fills.
It was also difficult to find dive-computers capable of tracking dives on gas mixtures other than air, because these were made only by a couple of companies such as Dive Rite and Cochran, which had very small sales and distribution networks.
Nitrox-diving would have remained a specialist niche market, but in 1995 PADI climbed aboard the nitrox wagon, universal public acceptance followed, and suddenly all the other mainstream training agencies followed suit.
Simultaneously, big manufacturers such as Suunto, Oceanic and Aqua Lung added nitrox-capable computers to their product lines. This happened so fast that within a couple of years it was hard to find an air-only computer any more.
In 2011, a similar shift seemed to take place when PADI announced a range of rebreather training courses. Before that, only boutique agencies such as IANTD and TDI had been teaching divers to use rebreathers, and it was still very difficult to find dive-centres that could provide support for rebreather-divers.
However, the arrival of PADI’s new courses encouraged more dive operations to take a closer interest in the technology and set up rebreather-friendly facilities. It also persuaded major equipment manufacturers to look at developing their own units and add fixed-PO2 capability to dive-computers to help rebreather-divers track their decompression status.

New units were designed with an eye to making rebreathers less demanding for the user, tackling some of the drawbacks of earlier systems and reducing the potential for diver error.
They had important features such as:
1 Cheap, reliable, pre-packed, disposable CO2-absorbent canisters
2 Carbon-dioxide monitoring technology
3 Real-time decompression calculation
4 Mask-level status displays (reducing the need for divers to monitor their gauges constantly) and
5 Alarm-driven switching to open circuit.

The addition of such features meant that the new units did not impose such stringent demands on the diver as previous systems.
Simply put, the primary task of monitoring the system was handed over to the electronics. The user just had to follow warning messages that would flash when the machine detected a problem.
This is a similar concept to the way in which modern cars are designed. You don’t have to understand what’s happening under the bonnet; you just have to keep to the service schedule and take the car to the garage when a warning light comes on.
These developments were a major step forward in terms of rebreather safety, and they did indeed lead to some market expansion. However, the rebreather revolution stalled again.
Divers, it seemed, were still not ready to change the way they dived and abandon open-circuit diving in any great numbers.

Common sense suggests that for any replacement technology to be accepted by the majority of sport-divers, it must not only cure the problems of diving open-circuit, but must also match the advantages.
Otherwise divers will simply be exchanging one set of problems for another, and it will be tricky to convince them that they really need it.
The advantages of open-circuit systems are that they are readily available, robust and tolerant of rough handling, resistant to diver neglect, easy to maintain, economical, simple to operate and easy to learn to use.
The disadvantages are that they are heavy, uncomfortable, noisy and limit a diver’s in-water time.
Even the new generation of sport rebreathers cured only the noise and in-water time problems. They were still heavier and more uncomfortable to carry than open-circuit systems and did not match any of open-circuit’s advantages, being expensive, fragile, complicated and time-consuming in terms of preparation and maintenance.


The majority of the world’s open-circuit divers don’t own their own scuba cylinders. This reluctance to purchase is not a reflection of their commitment to the sport; it just means that they prefer to hire because either they don’t want to store and maintain cylinders, they live somewhere from which they always have to fly to dive, or they have calculated that it makes sound economic sense not to buy.
If a diver has never bought a cylinder, it seems unlikely that he or she will ever buy a rebreather.
This means that for rebreathers to replace open-circuit systems as a diver’s first choice, they must become universally accessible.
Units need to be cheap enough and reliable enough to persuade dive-centres and liveaboards to invest in the new technology and have rebreathers available for hire.
For this to happen, there also has to be conformity in design and use. At present, every model is different, and certification on one unit does not qualify a diver to use another.
I know that the comparison is not entirely fair, but imagine how difficult it would be for dive-operators to offer rental regulators if divers were restricted to using only the brand with which they had trained.

So are rebreathers the equipment of the future? The answer would appear to be, “not yet”.
However, we’re on the right path and it seems likely that one day, and it may be soon, someone, somewhere, will introduce a rebreather or some other technology that fulfils all the practical requirements I listed, and captures the imagination of divers, as Cousteau did with the Aqualung all those years ago.
Then we will all be able to dive on ultra-silent machines that give us the maximum amount of dive-time possible within physical and physiological limits, warn us when there is a problem and advise us on exactly what to do to solve the problem.
They will be available everywhere, light, comfortable, fuss-free, easy to set up and intuitive to understand.
There will be no need to question whether we really need one of these machines. The answer will be obvious, and we will finally be able to consign Cousteau’s Aqualung to the museums.

Read more from Simon Pridmore in:
Scuba Confidential – An Insider’s Guide to Becoming a Better Diver
Scuba Professional – Insights into Sport Diver Training & Operations
Scuba Fundamentals – Start Diving the Right Way

All are available on Amazon in a variety of formats.

Appeared in DIVER May 2017


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