Welcome back to the channel, SD fans. Closed circuit rebreathers, or CCRs. These are undoubtedly
cool pieces of kit. Maybe you dive one yourself already, but if not, most of us will have
seen divers on CCRs at our local sites or on dive boats with us. They look daunting,
complicated pieces of kit, and they do require a particular mindset to dive them safely – but
are they as dangerous as some people make out? In this video, I’ll give an overview
of CCRs and why they might – or might not – be for you.
If you haven’t been here before, my name is Mark, I am the editor-in-chief of the Scuba
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Now, let’s dive into the video!
I am always a bit dubious when a piece of diving equipment warns you, in no uncertain
terms, that diving it without the proper training will lead to your death, but that is what
you find emblazoned across most closed-circuit rebreathers, some in a more in-your-face fashion
than others. Add to this the sad fact that many of the
diving fatalities I have had to write about over the years have involved CCRs, including
long-time Scuba Diver contributor and friend Gavin Anderson, who tragically died while
diving his rebreather off Scotland. Combined, this was enough to have me steer
clear of CCRs. I may have been diving for over 35 years and have thousands of dives,
but I just didn’t feel that going the CCR route was right for me, although I could see
several massive advantages when it came to underwater photography in particular – no
noise, no bubbles, and extended dive times. However, over the years, technology has been
steadily advancing and there are more and more CCRs coming on to the market. And I finally
succumbed, qualifying first on the Poseidon MK6 CCR, and then the Hollis Explorer eSCR.
Both units had their plus points, but both also had their negatives. Neither had enough
allure to draw me away from my trusty open circuit rigs. I have literally just had a
trydive on a Hollis Prism 2 CCR, which has been around for several years, but is now
hitting the UK market hard as it has finally received its CE approval. I have to say, using
this unit was an eye-opener, and with its compact size, Shearwater computer and very
low work of breathing, it was a very pleasant experience. However, the price point of several
thousand pounds is wince-inducing, until you factor in the ever-increasing cost of mixed
gases, but more on that later. Let’s go back to CCRs and the dangers connected
with them. I have heard it said many times to me that some of the best CCR divers are
people with little open circuit experience. They have not got into the habits and muscle
memory of open circuit diving, so they don’t have anything to ‘unlearn’ before they
start to ‘learn’ how to dive a CCR. You really are back to being a beginner again
when you move on to a CCR, regardless of how many recreational and technical open circuit
dives you have done, and sadly, many fatalities are people who are trying to run before they
can walk, so to speak. You need to slowly increase your depth as your time on your unit
increases, but alas, many charge straight in thinking they can dive a CCR to the depths
they were doing on open circuit before. Diving on a CCR is vastly different to diving
on open circuit. Perhaps the biggest difference between the two is buoyancy control. As an
open circuit diver, once we are neutrally buoyant, we can go up and down by breathing
in and out. After years of open circuit diving, this becomes a very natural thing to do. However,
this all goes completely out of the window once you move on to a CCR. Breathing in and
out makes absolutely zero difference to your buoyancy, as the gas in the breathing loop
is either in the counterlungs or in your lungs. Cue lots of swearing when you first start
diving on a CCR as you crash into the seabed, or swim into a rock, as your ingrained habit
of breathing in to arrest your descent, or to rise up over an obstacle, makes no difference.
You soon start to get to grips with remembering to use your wing and/or drysuit to control
your buoyancy, but as soon as you begin to relax a bit, that muscle memory comes back
into play and the swearing starts all over again. This alone can take several dives to
master CCR buoyancy. On top of that, you have to be bang on your
game monitoring what gas mix is in your breathing loop. Yes, the CCR will have oxygen sensors,
and maybe even carbon dioxide sensors, depending on the model, but you still need to be monitoring
what the computer is showing you on its display. When diving a CCR, the gas you are breathing
can kill you if the partial pressure of oxygen in the gas is too high, or too low, or if
the partial pressure of carbon dioxide is too high. Your CCR should give you a warning
on the computer screen and on the heads up display, but you also have to notice and react
to these warnings. On my trip to Scapa Flow when I was diving on the Hollis Explorer,
there was a chap on board who was diving a complex technical CCR who routinely went into
the water with it flashing red warning lights and bleeping away. When your unit is doing
its level best to tell you not to dive, maybe it is a good idea staying on the boat…
In fact, the statistics show that the vast majority of CCR deaths are down to human error,
not a problem with the rebreather itself. Take check-lists, for example. On both my
rebreather courses, we referred to a checklist every time we built up the unit to ensure
that everything had been correctly configured and confirmed. When I did the trydive on the
Prism 2, we ran through a check list step-by-step – and even people who had been diving the
unit for more than eight years said they still use the check list during preparation. It
is better to be safe than sorry – you only need to miss one single thing and it could
be potentially fatal – yet I have witnessed people prepping their CCRs and going diving
without a check list in sight. At the end of the day, it is all down to personal choice
– but given many deaths are down to the oxygen cylinder not being turned on, the scrubber
not being correctly fitted and other elementary mistakes that would have been picked up and
dealt with when using a check list, is it worth the risk?
So if CCRs are this complicated and require this much effort and concentration to dive
them, why would you go down that route? Well, there are many reasons people opt to dive
CCRs. Photographers and videographers love the fact that CCRs are completely silent,
so you can closely approach your marine life subjects without spooking them, and the vastly
extended bottom time means you can spend longer getting those perfect shots or footage. However,
the big winners with CCRs are technical divers. Closed-circuit rebreathers allow tech divers
to make deep, complex dives in open water, and in overhead environments like caves and
wrecks, which would just not be logistically possible on open circuit due to gas demands.
And with the ever-rising costs of mixed gases, a CCR can essentially pay for itself within
the space of a dozen or so dives, as you use a fraction of the gas you would on open circuit,
so that initial purchase price does not seem so out of this world.
I would say, if you are tempted to go down the closed-circuit rebreather route, take
your time and look at all of the different units on the market. Talk to instructors on
the different models, get their take on things, and then once you have narrowed down your
selection somewhat, go for trydives to see what they are like in the water for yourself.
If may well be at this point you decide that a rebreather is not for you, or you may just
be bitten by the bug. Just remember – learning to safely dive CCRs needs extensive training,
and while you are diving on one you need to be constantly vigilant, monitoring the gas
in your breathing loop. More so, you need to be prepared for the more-intensive regime
of cleaning and preparation that is needed both before and after a dive on a CCR. If
you have the right mindset, and commit to the strict routines required to dive them
safely, CCRs can open up a whole new world to you. If you are not the sort of person
to be absolutely fastidious in your preparations and cleaning regimes, or willing to accept
that you are going to be essentially a beginner again when you first start out, I’d suggest
that CCRs are not for you and to stick with open circuit.
Do you dive a CCR? Why did you opt to go down this route? Or are you just considering going
closed circuit? And why? Leave your comments below, and if you have a question, fire away
– if we can’t answer, maybe someone in our community will be able to. Remember, if
you enjoyed this video, be sure to subscribe to our YouTube Channel, and check out our
ever-growing playlist for more educational and inspirational videos.
As always, stay safe – and if you are going diving – on open circuit or a CCR - enjoy!