Tech Diving: Rebreathers…
By Steve Lewis
So, you’re looking at taking the big step into rebreathers, are you? Let’s chat.
It’s okay, your secrets are safe with me. I’ll admit it, I have owned a few rebreathers myself. At last count, there have been twelve. But no worries, I am getting better, the psychotherapy is working, and there are only two sitting in my scuba shed right now.
Whatever the word is – you know, the one reserved for politicians, telemarketers, and for those who knock on the front door just as you’re jumping into the shower – well that’s the word that best describes how I feel about rebreathers…most of the time.
However, please don’t get me wrong. There are times when I will not dive anything BUT a rebreather, because it is simply the very best option for the job in hand.
So perhaps I should start by trying to explain the dichotomy.
When they are set-up correctly; when all the assembly and pre-dive checklists have been fulfilled and go smoothly, when every aspect of the rebreather unit is working as it should, they are great. When all those necessary details are squared away, there is nothing more relaxing, nothing more comforting and peaceful, and nothing more fun to dive than a rebreather.
The benefits of abundant warm, moist gas being delivered with exactly the “right” balance of oxygen to diluent are hard to beat. Rebreathers often have the added and related benefit of delivering their owner back on the surface in better shape physically and mentally than when they started their dive.
Decompression stress is lessened compared to someone doing a similar dive on traditional open-circuit gear. Also, a rebreather diver has not had to hydrate and warm-up every lungful of gas, and because of that, his or her fatigue level is likely less. And on a long-deep dive requiring helium to cut both the effects of nitrogen narcosis, and to help manage loading of central nervous system oxygen toxicity, the rebreather diver has more cash left in his or her pocket at the end of the day to buy a post-dive celebratory round of cappuccino, ripasso, or whiskey sours for their dive buddies.
And, perhaps the least talked about benefit of all for the tire-kicking public considering a rebreather purchase, if anything does hit the fan at depth, the well-trained, well-practiced, properly kitted out and aware rebreather diver has many more options to get safely back to the surface than team members breathing open-circuit gear; many, many more options.
All told then, when everything has been done correctly, according to Hoyle, the user’s manual, training and experience, well then, rebreathers are not only the most comfortable and easiest thing to dive, but they are also the safest option.
All in all, not a bad equation.
But being a realist gets in the way of me being that cheerleader of CCR diving you see prancing around at your local dive site telling all and sundry that, “Once you start diving a rebreather, you’ll never go back to open-circuit!” Frankly and honestly put, rebreathers are exactly the right tool for only a very select and very small niche in the scuba diving community. At least, in my opinion.
Without argument, for that select and niche market a rebreather of one flavour or another is the perfect solution for most dives, but that doesn’t change the fact that it’s a small and select grouping. And that reality influences my enthusiasm entirely, to the point where I’ve possibly talked more punters out of buying a rebreather than I’ve talked into it. And that is not the best career move for someone who’s served as a product consultant and factory-sanctioned instructor-trainer for a couple of rebreather manufacturers!
So, let’s get back to some of hard facts.
First off, if your idea of putting your dive gear away at the end of a trip is to reserve a corner of your garage or tool shed because, “It doesn’t matter if the floor gets wet, and piled up like that in the corner my dive gear is out-of-sight and out-of-mind until I next need it,” please turn away now and don’t look back. Chances are better than a guess that you’ll be wasting your time and money. After a few weeks of being ridden hard and put away wet, you’ll be sending your unit back to the manufacturer for a major overhaul and rebuild. And that’s the best-case scenario.
If your idea of putting your dive gear away is piled up in the corner, please turn away now and don’t look back
However, if you are reasonably meticulous, enjoy keeping your stuff looking good, and as a personal rule love to put things away in their designated spot – are ALL the bits and pieces of your socket set present and put away in the right place – you have passed the first barrier.
At their very basic, rebreathers are actually as simple to maintain as rinsing with fresh water, disinfecting the breathing loop and counter-lungs, drying them, and then putting them where spiders, chipmunks, and bugs can’t set up home. The other basic chores include emptying the scrubber material, and making sure the head, controllers, and oxygen sensors are stored someplace warm and computer-friendly. But if you have doubts, redirect your rebreather fund toward that trip of a lifetime you’ve been thinking about.
Okay, second barrier. How many times a month do you dive? Perhaps that should read, how many times a week do you dive? You may, like me, live in Canada and weekly dips are a challenge for part of the year at the best of times.
Regular use and a deep familiarization is a prerequisite to staying safe. Rebreather diving goes a whole lot better when you remember precisely where the breathing thingy plugs into without consulting a unit schematic.
Following the manufacturer’s checklist helps – and is a required safe-practice – but a checklist is not infallible and isn’t going to help if it lacks precise detail and you can’t recall, for example, which side of flange C is the one that points in the direction of gas flow.
Also, the skillset needed to run a rebreather in the water is a mite more complicated than “breath-in, breath-out, repeat as necessary.” All skills are perishable, and if it’s been a few since you last practiced a diluent flush or ran your unit semi-closed, or if for instance you aren’t sure what the appropriate sequence of actions is to manage and deal with a stuck solenoid safely at depth, you need a practice dive or even a full refresher before venturing anywhere interesting.
A good buddy recently sold one of his CCR units because even though he was an active instructor on it, he’d been unable to put in any time on that particular unit for several months. “I love the unit,” he said a little sheepishly. “But I’ve forgotten how to run it safely.”
So, if you are an avid diver who is able to invest the time, effort and money if keeping skills sharp and experience current, welcome. You have made it passed barrier number two.
Next: what type of diving do you do? Are you a photographer; do you shoot video? Answer yes to either of those and you’re definitely a candidate for a rebreather. Your interactions with marine life are likely to take on a new level of intimacy when you are not spewing out a stream of noisy bubbles several times a minute.
Okay, another question in the vetting process! Do you currently spend the equivalent of a semester or two of college tuition on helium?
The gas efficiency inherent with a closed-circuit rebreather truly is remarkable, and it can show itself in bold black (or red) figures when it comes time to balance the books. On a recent live-aboard the average cost of helium for the CCR team was around one-fifth of the cheapest bill for one of the folks diving open-circuit!
Final question: do you have concerns about being able to afford a CCR?
This is a lot like the story about the luxury-car salesperson who tells a friend that if a customer asks the price, nine-times out of ten, they can’t really afford the car.
Now don’t misunderstand, everyone has to be price-conscious, but the initial investment in a CCR and training, and keeping up familiarity by diving it regularly is expensive. If you’re on a tight budget, be realistic about the required spend to get into CCR technology.
Now, a totally manual bare-bones sidemount unit from Kiss is going to cost a third to half the price of a state-of-the-art, expedition-grade Red Bare unit with the appropriate bells and whistles, but neither is exactly chump change. (And of course, both are primarily designed for very different applications. What that means in practice, is you may want to buy more than one type of unit. Did you just scream?)
Training is going to cost around $1500 and will take seven days – so factor in travel and living expenses for you and perhaps your instructor during your training.
If all that sounds feasible and you think you’re a good candidate for CCR, there’s one more question. I know I wrote final question one step back, but I lied.
Are you in decent shape… as fit as a butcher’s dog? An alarming number of “accidents” on rebreathers have had diver fitness as a factor. This is a dodgy topic and one that some instructors/sales people ignore, and one that one has to be careful about; however, age/weight/fitness related issues have been cited in a number of fatalities and near-misses. I have heard about a growing number of instructors who are very particular about taking on students who may be at risk because of these factors. They are asking for a very thorough medical sign-off. Again, if you have doubts, please think long and hard about your suitability for the added strain of carrying a CCR, bailout bottle(s) and suddenly having the potential to dive deeper, longer and harder than you are used to.
The message here is that a CCR might be the best thing to happen to you and your diving; just be realistic about the connection and appropriateness of it for you.
Okay, time to ‘fess up. I have to go now and pack one of my CCRs for a cold water wreck diving trip. In this particular case, my rebreather (a Hollis P2 in case you’re interested) is really the only thing I can trust that’ll do the job I want it to do.
Steve Lewisis an author, adventure travel consultant, and a technical diving instructor-trainer/evaluator. He lives in a small converted 19th-century schoolhouse in the wilds of Muskoka and has what he terms “the good fortune” to travel around the world to lecture and teach.