I JOINED THE FIRE BRIGADE in the late 1970s. My first posting was in Guildford. There were “old hands” on watch with 25 or more years’ service behind them. Some wore full sets of dentures, and on night shifts placed them in glasses of water by their bedsides.
As a young joker, I thought it was funny to sneak about in the dark and swap their false teeth around, so that a “shout” in the early hours would see them pop the wrong sets into their mouths.
Half-asleep and groggy, they would rush to the pump knowing that something wasn’t quite right. They would try to swap the ill-fitting sets with each other, as I sat in the back of the cab crying with laughter.
The reason so many otherwise fit and healthy firemen had such poor dental records in that era was that for 20 or more years they’d been using rebreathers for respiratory protection.
The emergency services of the day used Proto sets built by Siebe Gorman, introduced in 1914 and replaced with open-circuit compressed-air breathing apparatus around 1974.
The Proto set consisted of a divided rubber breathing bag containing Protosorb, which absorbed the carbon dioxide released from the body during exhalation, passing the air back through an oxygen supply and making it possible to rebreathe.
The problem was that when the Protosorb got damp it released acid that, over time, rotted the users’ teeth. Bad news for the old guys, but seriously entertaining for the young buck!
I share this story to show that rebreather technology has been around for a long time. What is new is a carbon dioxide scrubbing material that doesn’t rot your teeth, and state-of-the-art electronics that drive the machines.
Rebreathers offer divers longer, silent dives with maximised no-stop times. They work on a simple principle, but can be complex to dive with.
For the untrained, they may even lead to a catastrophic outcome. No one should dive with a rebreather without the training to do so.
For this reason the various rebreather manufacturers have set up a network of instructors offering training and certification that is mandatory before purchasing or diving any rebreather.
In conjunction with the manufacturers, unit-specific training courses have been produced by most diver-training agencies, and instructor-trainers appointed to “cascade” the information and qualifications.
PADI has proved to be a forward-thinking training organisation, keeping pace with technology and diving trends, and this is reflected in its latest Self Reliant Diver speciality course, and in technical courses covering mixed-gas diving down to 100m.
With an increase in the number of divers using semi-closed and closed-circuit rebreathers, and the subsequent increase in manufacturers supplying units, it was only a matter of time before the agency added rebreather diving to an already impressive line-up.

PADI’S LATEST OFFERING will raise a few eyebrows, and possibly create a market for a new breed of scuba unit. PADI Rebreather Diver is an entry-level course for diving within the accepted recreational envelope (no-stop diving, and no overhead envi­ronments) to 18m, using rebreathers that meet the specifications appropriate for recreational divers.
Only R-type rebreathers meet the criteria for use with this qualification (see Jargonbuster overleaf). At the time I reviewed this course, the only unit available that met the requirements was the Poseidon Discovery Mk6, although the release of other R-type units from Ambient Pressure Diving and Oceanic were, I was told, imminent. No doubt more will follow.
I visited PADI Instructor-Trainer Vernon Vas at Surrey Dive Centre in Ripley to find out what it was all about. Vernon has been supplying training for divers since 1991, and qualified as a Course Director with PADI in 1997. He also delivers training through the agencies PSAI and TDI.
Vernon has owned and dived a number of different rebreathers over the years, but his weapons of choice are currently the APD Evolution Vision and the Poseidon Discovery Mk6. He was one of the first instructors qualified to teach the PADI Rebreather Diver course.
Accompanying me on the course was Sue Talbot, a PADI Master Instructor new to rebreathers who was looking forward to embracing bubble-free diving.
Before enrolling on the course, divers have to be PADI Open Water Diver and Enriched Air Divers or hold equivalent certification from other agencies. They must be 18 or older, with at least 25 logged dives.
The course consists of three components: Knowledge Development, Practical Application and Training Dives. Sue and I were given manuals to take home, study and, in the familiar PADI format, complete the reviews after each section.

I spent the next two days reading through the manual. It’s well-written, with a logical progression through the sections. There is no assumption of previous knowledge and all the theory I needed to know at this level was included.
The manual is generic to recreational rebreather diving, and must be read in conjunction with the manufacturer’s unit-specific manual. Being a swot, I had already downloaded and printed the Discovery Mk6 manual from the Poseidon website.
I’m glad I had, because it’s a monster, though again well-written. It covered everything I needed to know about the unit.
The following week Sue and I met Vernon at the dive centre for a classroom session. Vernon checked our completed knowledge reviews, explaining in detail any points we’d missed or answered incorrectly, and ensured that we had a sound understanding before moving on.
This was followed by a discussion on how we should dive with the units. Using the Poseidon manual, we reviewed how to monitor and read our displays and gauges, with an emphasis on understanding the heads-up display (HUD).
Vernon put various problem scenarios to us and asked how we should react to them. The solution to almost all was to switch to open circuit via the unit’s integrated bail-out valve (BOV), and ascend at a safe rate to the surface.
At Open Water level, there’s no requirement to dive with off-board bail-out gas in the form
of side-mounted cylinders, though diving any deeper they would be essential. Vernon would carry a side-mount on all our dives, as this is a requirement for instructors.
Lunch was followed by the final theory exam, consisting of 75 multiple-choice questions. The pass mark is 80%, and Sue and I breezed through it. Well, we’re both just girlie swots!

It was time to roll up the sleeves and get our hands on some units. Vernon gave a practical demonstration of how to assemble the rebreather and insert a new pre-packed scrubber. Cylinder contents were analysed before connection and mushroom-valve functions were checked.
The comprehensive pre-dive checks were demonstrated, and Sue and I both followed
suit with the units we would be diving.
Having a checklist makes sense, and this is available in the form of a slate.
We then covered dive-planning, with an emphasis on staying within the limits of the scrubber, bail-out gas and maximum depths.
Finally, we were shown how to disassemble, clean and disinfect the units before packing them into the back of Vernon’s truck. We were off to the pool to get wet.

At the pool, we went through the pre-dive checks we had practised earlier in the day.
Every dive must be preceded by these for safety.
Pre-breathing through the loop (ensuring that your nose is blocked) “warms up” the scrubber and gives the unit a full function test before taking it under water.
My first impression of the Discovery was of just how lightweight it is, weighing in at little more than my scuba unit with a single steel cylinder. The mouthpiece and loop seemed a little bulky at first, but I soon got used to it.
Over the two dive sessions, Vernon briefed us on the skills he was going to demonstrate
and get us to perform. Buoyancy can be tricky when diving with rebreathers, so time taken to get weighting and trim just right is well spent.
The first skill was to open and close the loop, enabling us to breathe through the BOV, something we would be practising a great deal throughout the remainder of the course.
As the evening wore on we performed a variety of skills, including removing and replacing the mouthpiece under water and on the surface; flooding and clearing our masks; hoisting our loops above our heads to drain any water and again switching to open circuit via the BOV and ascending to the surface.
Other skills covered were hovering, neutral-buoyancy swims and swimming without a mask. After the session the units were cleaned, stripped and replenished ready for our next dives.

The following day, we were off to see my old dive-buddy and owner of Wraysbury Dive Centre, Richard Major. I had called him to find out the water temperature.
“A balmy five degrees,” he said.
“Oh ****,” I said.
“Yeah, but the visibility’s awesome,” was his reply. I was looking forward to it.
At Wraysbury we were ready to start the open-water component of the course, which consists of four dives over two days.
The pre-dive checks were completed before entering the water. Weight requirements were re-evaluated; it’s amazing how much more you need to compensate for a bulky drysuit.
The dive started with bubble-checks, then we swam to a training platform. I enjoyed breathing the warm recirculated air that’s unique to rebreather diving, a real bonus in the frigid January waters.
Sue and I took turns demonstrating skills while Vernon assessed our performance. We bailed out to open circuit, and then to our buddy’s alternative air source.
We hovered, drained our loops and flooded and cleared our masks while swimming around above the platform, terminating the dive with a bail-out and ascent, simulating an emergency.
The second dive was a repeat of the first, with the addition of deploying DSMBs. Again we finished by cleaning and preparing our units for the next day.
Day two saw us back at the lake, kitted up and conducting pre-dive checks. Vernon’s unit failed the positive pressure test. A small split in the corrugated breathing hose was the culprit – a quick phone call, and a replacement was delivered swiftly by his shop manager.
The unit wouldn’t allow him to dive until the test was passed, proving that the Discovery’s electronics didn’t miss a trick.
With his unit fixed and retested, it was into the water for dive three.
We repeated the core skills already covered with the addition of dealing with an unresponsive rebreather diver scenario.
The final dive saw us repeat the core skills, yet again ensuring that they now came naturally.
Near to our agreed time limit, Vernon’s rebreather started to warn him of a cell error, instructing him to bail out to open circuit and end the dive. The warnings were visible to both Sue and I via the back-mounted display on his unit, so it was no surprise when he switched to open circuit and signalled that the dive was over.
After disassembling, cleaning and disinfecting our units, it was time for some “loud whoops and high fives” (come on, it’s another PADI course) as Vernon awarded our qualifications.

I FOUND THE COURSE extremely enjoyable and very well run. The PADI learning materials along with the unit’s manual make for a huge read, however, and enough time needs to be allocated for the trainee to thoroughly digest everything.
If your buoyancy is right, the whole process is a doddle, so take your time ensuring this.
You must be prepared to allow time for the pre-dive checks before every dive and, most importantly, whatever happens, warnings must never be ignored!
I certified as a technical rebreather diver in January 2004, and took delivery of an APD Inspiration Vision the following March. I’ve logged hundreds of hours on my own unit diving exclusively in UK waters, but the logistics and cost of taking it abroad are prohibitive.
With type-R units already appearing for hire in some Red Sea resorts and on liveaboard fleets, the qualification I’ve earned is likely to get used. Eighteen metres is deep enough for me when I’ve got my camera. Should you need to go deeper, you can always take the PADI Advanced Rebreather Diver course, and this can be tagged along with the one reviewed here. Much research and development has gone into producing the specification for the type-R rebreather, and the outcome is a unit designed to fly itself, leaving the diver to enjoy the benefits of rebreather diving.
And there’s an added bonus – you get to keep your teeth!


  • Surrey Dive Centre, 01483 225699, www.surreydivecentre.co.uk. Vernon Vas offers the PADI Rebreather Diver course with unit hire for £650, or £500 with your own unit. Discover Rebreather Diving experiences cost £50.
  • PADI: www.padi.com
  • Poseidon Diving Systems UK: 01420 84300, www.poseidon-uk.co.uk. A Poseidon Discovery Mk6 closed-circuit rebreather costs £4700.
  • Wraysbury Dive Centre: 01784 488007, www.wraysbury.ws

The PADI Rebreather Course Showcase
Centres offering this course.

The ways in which rebreathers are controlled fall into various categories:

Electronic Semi-Closed / Closed-Circuit Rebreather (eSCR / eCCR):
Electronics control the setpoint throughout the dive, adding oxygen as needed. They
also warn you if there are any problems.

Manual Semi-Closed / Closed-Circuit Rebreather (mSCR / mCCR), also known as Diver-Controlled (dcSCR / dcCCR):
Electronics tell the diver the PO2 and may provide warnings, but the diver must monitor and manually inject oxygen as needed to maintain the setpoint.

Recreational Semi-Closed / Closed-Circuit Rebreather (rSCR / rCCR):
An eSCR or eCCR suited to recreational, no-decompression diving. The unit must:
  • self-initiate or warn the diver if the electronics are not turned on when he or she starts to use it
  • use pre-packed scrubber canisters. It will not operate, or will warn the user, if the canister is missing
  • have a system for detecting CO2 in the breathing gas or estimating the scrubber duration
  • provide warnings for low or closed gas supply, low battery life and high or low PO2.
  • be fitted with an open-circuit second-stage regulator, supplied from the diluent cylinder for sharing gas
  • have a “black box” data recorder function
  • have automatic setpoint control
  • have a heads-up display (HUD) warning system in the diver’s line of sight during normal diving
  • be fitted with a bail-out valve (BOV) operable with one hand
  • provide electronic prompts for predive checks
  • have undergone nationally or internationally recognised third-party testing against an appropriate standard. Examples would include meeting EN14143 (and attaining CE marking).