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By Cedric Verdierby Cedric Verdier
Technology is something wonderful. A few years back, Trimix computers were as common as a friendly Taxi driver in a traffic jam. And CCR computers were almost non-existent. The few models available on the market were the size of a toaster and had the same memory.
Nowadays, the Tek Diving market is expanding and computer-controlled diving is becoming the norm. People enjoy the flexibility of a computer when it comes to multi-gas, multi-depth and multi-day diving.
The now famous VR3 and Nitek are quite popular, with HS Explorer and Cochran following close behind.
But not all multi-gas computers are born equal. A new computer has been launched on the market that could definitely change the way Technical divers select their so precious instrument. After the F1, a digital depth gauge, Liquivision made the X1, a surprising computer with a lot of interesting features.
- The first thing you have to admit when you see an X1 for the very first time is that the X1 doesn’t look like any other dive computer:
It’s incredibly small (half the size of a VR3) but with an extremely bright display. This organic LED display makes all the information easy to read in any position and any environment. The screen is strongly built and scratch resistant, and you can adjust the brightness or even the size of the digits.
- There is no button that can break. You access all the functions by tapping the computer on its different faces. You can adjust the strength you ’d like to tap the X1, depending if you are the size of a Chihuahua dog or if you have a rather sadist mentality and like hitting hard.
- The battery is rechargeable and there is no access to it. The result is the lack of potential failure due to a flooded battery compartment. But because the computer is a little bit greedy, you need to re-charge the Lithium Polymer battery quite often, even if its lifetime is about 10 years.
- You can choose which decompression model you want to use. Thanks to different developers, you can actually upload various algorithms from V-Planner Live (a specific version of V-Planner) to GAP X1 (with Buehlmann model). Depending of the 3rd party software you choose, you get access to very different functions (Nitrox, Trimix, CCR, digital compass, etc).
- (to be continued)
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By Cedric Verdier
There is no safe Technical Diving without proper preparation. But this preparation is more than just equipment checking, thorough dive planning and “What Ifs”. Here we speak about long-term preparation.
Imagine how strenuous a technical dive could be and its impact on your body. You carry tons of tanks, cases, bags and equipment, travel for hours in an uncomfortable position, gear up with a dry suit under a tropical sun and wait long minutes before being able to jump in the water. And this just starts to put your body under stress. You still have to swim to go down, swim on the bottom, swim to go up, on-gas, off-gas, fight against the current and drag of your deco tanks, your bailout tank(s), your huge twinset (the one you nicknamed Potemkine!) or your favourite rebreather, swim at the surface, climb the ladder or the shore and carry everything again! And some people think we do that for fun!
It’s quite obvious that preparing this kind of dives goes far more beyond resting the evening before the dive and drinking a so-called energy drink a few minutes before kitting up. It’s an over-the-year preparation. More, it’s a lifestyle!
The benefits of fitness training
- A better cardiovascular system
A better cardiovascular system means a lot for your body. It doesn’t only improve your dives but also your general health.
Some studies show that there is a relationship between VO2max (your maximal O2 consumption, i.e. the ability of your body to efficiently transport and use the O2 in your lungs) and risks of Decompression Sickness.
And a better use of the Oxygen means a better/slower ventilation. You are less exerted if you have to swim for a long time, or harder than usual, and it becomes easier for your body to get rid of the CO2 you produce.
- A lower Body Mass Index
The Body Mass Index (BMI) is a way to determine the ratio between fat tissues and muscles in your body, based on you age.
A lower BMI means a few things for a rebreather diver:
- Less fat and more muscles is a good way to decrease your susceptibility to DCS. Because of a higher vascularisation, muscles tend to be less prone to DCS than poorly perfused fat tissues.
- Muscles are heavier and less buoyant than fat tissues (1.10 gr/cm3 for muscles and only 0.90 gr/cm3 for fat tissues). So a lower BMI means a less buoyant body, needing less weight on the weight belt, something all divers should appreciate. And with less weight, rebreather divers have usually a better trim.
- More muscles also mean more strength, something that can prove to be useful in case of an unexpected situation (fighting against a strong current, holding on a shotline, etc) or an emergency (helping another diver to surface, rescuing a diver and removing him/her from the water, etc).
The Body Mass Index can be calculated by different complex equations based on the skin thickness, or more simply, with modern digital scales.
Obesity is when your BMI is over 20% if you are under 35 years of age (31% for women). But if you are older than 35, then obesity only appears if your BMI is over 25% (37% for women). So check it out on a regular basis!
- More comfort
Good body fitness is of paramount importance for your comfort level at the surface and underwater.
- Before the dive: It gives you more strength to carry the tanks and all your kit, noticeably reducing the pre-dive stress. It also helps you to stand up, walk and jump in the water with all the gear on.
- During the dive: swimming because less tiring and less stressful, allowing your muscles to better avoid cramps. You swim more efficiently and more relaxed and your gas consumption (or your Oxygen consumption if you dive with a rebreather) doesn’t go through the roof every time you have to swim slightly harder.
- After the dive: with the post-dive decompression stress, your body suffers to a certain extend. But one of the most stressful events for it is to climb a ladder (or anything else), minutes after surfacing. Your heart has to pump faster and harder to supply blood to your muscles when you already have a peak in bubble formation in your bloodstream.
(to be continued)
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By Cedric Verdier
You plan to explore on a deep virgin wreck? Your dream is to discover a unique cave system deep in the jungle? You heard about a Blue Hole miles offshore and want to give it a try? Chances are you’ll be diving in a remote location where emergency medical systems are more frequent and up-to-date than traffic lights in Himalaya.
Anybody involved in the early stage of an expedition had to answer a few questions first:
- Is the place I plan to go has the necessary infrastructure in case of emergency?
- What is an Emergency and what kind of emergency I may face?
- What do I need to bring in order to reasonably deal with any potential emergency?
In other words, how remote is remote and do we need a physician 24/7 with us?
Unfortunately, if you travel most of your time, you will sadly discover that quite a few medical facilities worldwide look like hangars during intensive bombings. Sometimes the medical staff is so busy that people run everywhere like if the news of Armageddon have just been broadcast.
So the first reaction would be to think: we have to be self-sufficient if an accident occurs. Unfortunately this is rarely possible. So let’s try to find a compromise and let’s start with proper planning.
Emergency planning includes several steps:
- Assessing the risks
Any technical diver has been exposed to “What if” scenarios. For a remote exploration, the best option is to lock down all the team in a small room with only filthy sandwiches to eat until they come out with a comprehensive list of all the problems that could happen during the exploration, underwater and at the surface. You then have to review this list and remove what you can’t really deal with (tropical hurricane, tribal riot, terrorist attack using the Ebola virus, etc.).
(to be continued)
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By Cedric Verdier
I was recently one of the 2 deep divers to look for the bottom of Sra Keow, a cave system in Thailand. That was the 3rd expedition I did on the deeper part of this cave system. Questions were raised about the maximum depth I reached during this dive. Some people who werent even there questioned on various Internet forums we never reached the depth we mentioned on our press release (240m/785ffw). I normally don't participate in this kind of useless discussions, as people are more interested by the fight than by the actual facts. These Internet fights end up nowhere. They require plenty of time, a big load of aggressiveness and a full time Internet connection. I have none of them. I spend most of my time on dive boats or traveling. In this case though, some of my friends and students convinced me to clarify the story. If people want to have an objective opinion, they need both sides of the story. Reasonable and wise people can't judge someone's action without that. As Ben Reymenants, the other deep diver in Sra Keow, stated at the beginning of his dive report: before the exploration, all the deep divers agreed on a strict policy about public communication: the deepest depth reached by any diver will be the official maximum depth without distinction between the deep divers involved. This policy, already used by several teams of deep divers, has a very simple goal: avoiding useless competition, stress and unnecessary risk-taking within the team, to avoid any diver to try to be more "under the spotlights" by being the deepest one. By not publishing the maximum depth reached by every single diver, we thought that itd be the most reasonable decision to increase safety in an already risky exploration. The mission was to efficiently explore the bottom of the cave, not to encourage any "cow-boy attitude".
(to be continued)
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By Cedric Verdier
Previous episodes
Sra Keow, a name that becomes famous in Thailand. Almost two years ago now, a group of avid cave divers decided to explore this unique cave system located near Krabi, South of Thailand. Amongst the huge number of caves spread all over this limestone country, why did they choose this specific one? Because their instinct told them they will discover what is now the deepest flooded cave system in South-East Asia.
Cedric Verdier, Ben Reymenants, Mike Gad, are deep cave explorers who participated in one or several of the three expeditions conducted by the Asian Cave Diving Club in order to survey and map Sra Keow Cave in 2005, 2006 and 2007.
The shallowest part having been explored by a group by the name of TCDP a few years ago, the first part of the map looked promising and caught the imagination of these seasonal cave divers. In May 2006, Cedric Verdier and Mike Gad used their Closed-Circuit Rebreathers to set up a record dive at 201m, the deepest cave dive ever done in Asia-Pacific. After a 6-hour long dive, they surfaced with the satisfaction of having discovered a huge room sub-200m.
A new phase of the exploration was about to start...
June 2006.
I meet Ben Reymenant for the first time. He works at the recompression chamber in Phuket, Thailand, and is also an accomplished Technical Diver. I never had the opportunity to speak with him but when we meet at the airport, we come along almost immediately. He is an easy-going, always smiling bloke from Belgium and I can even speak French with him, something I don't do very often anymore.
We discuss about the wreck of the HIJMS Yamashiro, a very deep wreck I just explored in the Philippines. I also mention Sra Keow and his interest is immediate. Living just a couple of hours from Krabi, he decides to have a look. The project is already launched. We have to survey the deepest part of the cave!
(to be continued)
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By Cedric Verdier
A few months ago, a team of experienced rebreather divers living in South-East Asia, decided to explore the Sra Keow cave in Krabi, Thailand. This cave system was previously explored by the Thailand cave Diving Project but, because of the limitation of Open Circuit Scuba, nobody ever reached the deepest part of the main passage.
In a matter of a few months, three CCR depth records were broken, using stock units.
Cedric Verdier, a Technical Diving Instructor Trainer since 16 years, pushed the limits of the Cave to 201 m/ 663ft using a standard ISC Megalodon Closed-Circuit Rebreather with an axial scrubber and no major modification. This dive is supposed to be the deepest dive ever done with a Megalodon, and also the deepest cave dive/rebreather dive ever done in Asia.
Mike Gad, from Singapore, reached a depth of 191m / 626ft with a Delta-P Ouroboros CCR with no modification. Here again, it's supposed to be the deepest dive ever done with this unit.
During a previous expedition, Bruce Konefe used an AP Diving Evolution CCR to explore the same cave at 120m / 393ft, quite a challenge with a very small scrubber.
Sra Keow is a wonderful place. An easy access, a convenient location close to Krabi and its beaches, a scenic landscape, with some placid elephants who sometimes come nearby to carry tourists. This is supposed to be the deepest cave system in Thailand. Two entrances are connected together as the gateway to a giant kingdom with crystal clear visibility and easy access. The main passage is huge and it was impossible to see the bottom of the cave. This first expedition was such a success that they all decided to come back as soon as possible. Because of their respective occupations, nothing will happen before four months. The abyss had to wait for them.
(to be continued)
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By Cedric Verdier
When it comes to constant pO2 dive computers, most of the divers immediately think about the VR3 made by Delta-P in the UK or the HS Explorer made by Hydrospace Engineering in the USA. Most of discussions on the Internet focus on these two models, with sometimes strong arguments about the necessary features and advantages of one or the other. Decompression model, Graphic User Interface, reliability, customer service, it’s like toppings on a pizza, everybody has an opinion about what is good or bad.
Until recently, one of the main complaints about the VR3 was the Buehlmann’s algorithm modified to incorporate once-in-a-while deep stops (a la Pyle). But the current trend in deep diving is more about dissolved gas models. With the release of the new version, the VR3 is now offered with a brand new and shiny algorithm that is supposed to be based on VPM-B/E (even if people like Ross Hemingway, designer of V-Planner, confess that they didn’t participate in the development of the Delta-P’s VPM-B/E model).
Therefore I decided to buy a new VR3 in order to test it in deep trimix diving and determine if I actually increase or decrease my level of risks by using this computer.
Thanks to Mike Cochran, I also received a Cochran EMC-20H computer. Unlike the VR3 I didn’t have any previous experience on a Cochran product, as they are not very common in the different countries where I normally go underwater without blowing bubbles. According to the manufacturer, this computer is based on a “20 tissue adaptive modified Haldanean” algorithm. Sounds like a twisted bubble model…
Anyway it’s a constant pO2 computer one can use with helium-based mixtures, so it’s good for my dives.
So, time to test and compare!!!
In the 70m range: (Trimix 10/52, setpoint 1.2, square profiles)
I was very surprised to discover that both computers always gave me the same 1st deep stop. By the way, it was also the depth of the 1st deep stop on my VPM-B Tables and much deeper than the Vision electronics on my Evolution (Buehlmann with GF 20/80). That’s an interesting feature I didn’t expect from the Cochran.
But it was only the beginning of my surprises.
(to be continued)
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By Cedric Verdier
It was supposed to be a dive with no problem. One the Trimix dives you really enjoy doing. At least it was what I thought. A few hours later, I knew I was wrong.
Thailand, August 2006. Everything is prepared for a Trimix dive near Pattaya. The weather is not perfect but nothing bad, and the two Open Circuit Trimix divers I dive with don’t find anything to worry about during their dive planning. I just trained them as Instructor Trainers and they both come from Hong Kong where the conditions could be similar. A little bit of wind, small waves at the surface and some clouds in the sky. That’s it. The small boat that brings us is handled by a very experienced Thai captain and his sailor. They daily deal with technical divers and know the procedures and the area since many years. And as a matter of fact, the dive runs smoothly as we explore the bottom. There is a mild current on the bottom, mainly due to the tide, but the captain is aware of that and he knows that if we can’t come back to the boat, he will have to follow us during our drift deco. After 20 minutes on the bottom, we decide to ascend, everything being exactly according to the plan. Both my OC divers send their SMB very soon during the ascent and I stay close to them. Unfortunately one of them gets his reel jammed but we manage to pull the SMB back down. We’ll have time later to un-jam it. Time to sort out the all thing and we’re now almost 35 minutes into the dive. I have the feeling that we drift quite fast and I decide to also send my SMB to make sure that the boat follows us. 75 minutes Run-Time and it’s time to surface now. We slowly ascend the last few metres to discover that the sea is quite rough now. We also understand that we drifted quite far from the island we dived on. And we can’t see anything that looks like a boat.
After a few minutes to consider the different options, we try to evaluate the actual direction and speed of the current. Still no boat anywhere. I guess the skipper decided to protect the boat on the other side of the island when the weather picked up, and didn’t see the SMBs because of the waves. But whatever the reason, the situation is quite clear: we drift offshore in a sea that becomes worse and worse as we are not protected anymore by any of the small islands of the area. We think about different options but we finally end up with two: drifting or swimming. If we drift, we can use the SMBs, our lights, a mirror or an air-powered whistle to signal any boat, but there is no sun, the waves are quite high and more important, there is still NO boat! So we decide to swim.
(to be continued)
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