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MDC Take on the Rebreather

MDC Take on the Rebreather

MDC Take on the Rebreather


Dr Mike Gonevski

I have been toying with the idea of technical diving for a long time. Such a long time in fact, that it became one of those things that seem destined to slowly drift into obscurity under the heading: "I wish I had..."

So when the opportunity presented itself I jumped at it without second thoughts. Open circuit technical diving is becoming more and more financially difficult for the serious depths. The majority of the remaining supplies on this planet are in the US and Russia and as recent history has proved, they can and do whatever they want; hence the price of helium skyrocketing. Using a rebreather becomes not only attractive but obviously the natural choice. Even more so when we'll be learning to use the Megalodon rebreather, with some of its high profile customers being the US Navy, the FBI and NOAA.

Day One. A journey of a 1000 miles starts with the first step.

I consider myself to be a very experienced open circuit diving instructor and so is my dive buddy Robbie with whom we are undertaking this course. That surely should count for something, even if it is just not bolting up to the surface when the going gets tough... :) I'm slightly uneasy as all the training materials that I read beforehand about rebreathers had in big red letters warnings that if you don't monitor your gauges and especially your PO2 at all times you will die! It is only a matter of where and when. Undeterred by such statements however, as usual I entered training with a healthy dose of expectations and enthusiasm. This ain't my first rodeo after all. Our instructor Dennis Vessey has somewhat of a legendary status as far as the Megalodon rebreather is concerned, being involved in its development since its inception and the chief instructor for all of Europe. And when it comes to teaching the Megalodon rebreather to the American FBI (I cannot resist an Ali G moment: F.B. Aiiii), he is their number one choice as a man to go to for training. I'm pretty confident that whatever hurdles and obstacles we have to face,

we'll face them head first and always come up on top. He is going to be assisted by another rebreather instructor in training, a Danish Viking appropriately called Rune, who immediately struck me as somebody perfectly fitting the psychology bill for divers: stable psyche, self control and no anxiety in the face of adversity.

We start with building the Megalodon from scratch, assembling the different bits and pieces together using a checklist in the process. I cannot overemphasise the importance of the checklist as it can save your life. It demands that

you check all the "t's" and dot all the "i's", making sure that all bits are fitting where they are supposed to fit, all the millivolts are within the acceptable range and the Oxygen cells have enough spare life in them. They must be changed every year. People who can't afford or don't want to do that should not dive with a rebreather. The day that they were installed first should be marked with a permanent marker on them as well. Packing the scrubber with lime as tight as possible is another crucial element that has to be mastered, as it absorbs all the exhaled CO2. Its lifespan depends on the conditions of the environment - cold water diving reduces it dramatically. The FBI has gone even further and has it as an SOP after every dive 'Standard Operating Procedure'.

On average it lasts around 3 hours of diving but you should adhere strictly to the manufacturer's recommendations. Any deviation and you can become another casualty statistic. Just remember the red warnings all over the training manual... That being said, I summoned enough courage to ask the question that has been haunting me all day. With all the FBI and military training that he has been involved in, do we have to stand at attention and shout "Hooyah, Instructor Vessey!". Having been reassured that this is not absolutely necessary we continue the day finishing with a fully assembled unit. I could not wait for Day Two when we'll get wet in a swimming pool.

Day Two. The only easy day was yesterday.

This is the day when we have to master our skills in a confined water environment in preparation to handling the beast in open water. How lucky that we did, as the following days proved. The buoyancy will definitely be a challenge. Up until now while using open circuit scuba I'm used to controlling it just by inhaling and exhaling alone. The Meg is a whole different ball game. Due to the nature of rebreathers, a set amount of breathing gas circulates in a loop, so using your lungs as a buoyancy device can actually be counterproductive. There are two counter lungs in the Meg, strategically placed over the shoulders, allowing ease of breathing both during the inhale and the exhale phase. The rebreather also has a "wing", its own buoyancy device. On top of that I have to battle with a dry suit, making an effort not to embarrass myself shooting feet first to the surface. After a test of the rebreather on the side of the pool I cautiously enter the water. Yes! To paraphrase that old saying: "Look Ma, No hands!"- "Look Ma, No bubbles!" Only that this was usually followed by a loud crash... Let's see how we manage it this time. I'm listening to my own breathing, trying to determine if all the anxiety is making me breathe heavily like a COPD patient. I still have to monitor my gauges –you guessed it, if you don't monitor your PO2, it is only a matter of where and when. I'm struggling to maintain some sort of passable buoyancy, trying not to bounce off the bottom of the pool or off of each other too much. My only comfort is that when you start to use a rebreather you are an absolute beginner all over again. We master the same skills that we are expected to perform the following day in open water –The "Boom!", Flushing the loop, and the various emergency procedures –High O2, Low O2 and High CO2. Luckily for us, there is no information overload how to determine which is which, as the emergency procedure is the same –flush the loop and bail out. Bailing out comes easy and natural, as it is the good old familiar open circuit – I only hope that I'll never have to use it.By the end of the day I am relaxed and comfortable enough to start planning stealth missions in my head, sneaking on unsuspecting open circuit divers, pretending I'm the Big fish from Jaws. After three exhausting hours in the pool me and Robbie give the thumbs up. We finish the day pleased that we have not given Dennis too many extra white hairs...

Day Three. Hooyah!

We start the day going meticulously through the checklist of our Megs, being watched all the time attentively by both Dennis and Rune. It all seemed nice and easy the day before. Not so much now before the open water. There is still life left in the scrubber, so we concentrate our efforts on calibrating the unit, checking the loop and making sure that everything is nicely streamlined. The anxiety is building up. This is not a dress rehearsal. We get in our dry suits first and then manage to walk the steps down that lead to the water. Dennis and Rune are already on the water surface, patiently waiting as we battle with fins, bail out tanks and worst of all gloves that need extra lubrication to fit in. Why do they say "Fits like a glove" is beyond me – mine doesn't! I'm checking that my dive computer is in place, all my gauges are set exactly as planned, my bail out is within easy reach, my tanks are open, the SMB is in the right place, all the while pre-breathing the loop on the surface, making sure that there is no deviation in any of my gauges. The configuration when diving with a rebreather is slightly different than open circuit. Having an SMB is a must. As well as Heckler and Koch MP5 9mm submachine gun. Wait, this last one is optional. I take the plunge into the blue with a giant stride. The familiar cold water shock to the system – if I must compare it to something, it is like being hit on the head with a gold brick with a tiny slice of lemon attached to it.

I know that this is the description of the effect of a properly made pan galactic gargle blaster but since I have never had one, it always seems the most appropriate thing to compare the initial feeling of the cold water to. Everything is working properly, thank God for going through the checklist! Now here comes the fun part, maintaining buoyancy, checking gauges all at the same time, checking the PO2 and maintaining it manually - by now you should all know very well what happens if you don't - and trying not to be more than a couple of metres apart. I selfishly hope that Robbie is struggling as much as I do and by the looks of it, that indeed is the case. We stop and perform all the skills that we practiced in the pool the day before. It all comes back, despite the thick diving gloves allowing as much dexterity as picking up needles with boxing gloves. We finish the dive flushing the loop and breathing 100% Oxygen at a depth of 6m. It was a success!

Day Four. Birthday Boy.

We have planned two dives for the day and more skills, this time in deeper water. It is my birthday as well and I can't imagine a better way to celebrate than being underwater. It is exactly the same set up as all those years ago when I was going through my IDC in order to become a diving instructor. I'm pleased that history repeats itself. There is an obligatory piece of cake as it is still too early in the day for other refreshments. Wink, wink, nudge, nudge. We concentrate on using the check lists and go meticulously over each detail again. Our confidence is building up. Not enough to become arrogant though. It takes us less time to get in the water and every minute spent previously on the unit is helping. There are no short cuts. We perform the skills over and over again followed by a leisurely underwater tour of this world famous diving site. This is Stoney Cove after all and there is a bus, a helicopter and even a tank underwater. We finish every day with a debriefing where we discuss what went right or wrong and what to do the next time in order to avoid it.

Day Five. The rule of seven. Proper Previous Planning Prevents Piss Poor Performance.

I'm a little late, after been engaged in various recreational activities the night before (it was my birthday, remember). So I rush through the checklist and end up making three crucial mistakes. This 'gets me a proper reprimanding' but there is no time to waste for corporal punishment. I do everything properly the second time. It is our last day of the course and this time we are going in deep water. We are a lot more streamlined and comfortable underwater and our buoyancy is leaps and bounds better than what it was at the beginning of the week. It is so quiet that I can even hear when the solenoid is injecting extra oxygen. Some curious fish approaches, unperturbed that we do not belong to their habitat. Then suddenly they dash away, scared as it turns out by an approaching group of open circuit scuba divers and their bubbles. Hey, this would have been me only a week ago! It is raining heavily once we are back to the surface; one might even say cats and dogs. But you can't scare a diver with a few drops of falling water, right. We have a proper debriefing and I can't believe that this is over. Pretty much like with getting a driving licence, this is just the beginning and you have to hone your skills by doing it. In our case we plan on diving on the rebreather at least one day a week as we need, as Dennis says, at least 50 hours before we become proficient. More is better.

What strikes me as different with rebreathers is that there is not a set structure and a curriculum and no clear cut instructor student distance like the other courses I've done before. It is more akin to the mentor - student, or better yet, Jedi Master and an apprentice relationship which I find is crucial in order to succeed. It is not called "technical diving" for no reason. I cannot overemphasise the importance of checklists for preventing Mr Murphy (of Murphy's Law fame) from coming along for the dive. I consider myself very fortunate to have Dennis Vessey as an instructor as I definitely felt safer underwater.

I feel cold, wet but far from miserable driving on the way back home. The radio is blasting out Motorhead: "You know I'm born to lose, and gambling's for fools but that's the way I like it baby..." Diving with the Megalodon rebreather is certainly not a gamble but rather a safe bet.

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