I apologize for the extremely bad coloring of some pictures posted, but for I don’t have Photoshop on my laptop and the RAW conversion utilities I have tried in either Picasa, ORF Suite, BreezeBrowser or such are absolutely unusable without spending an absurd amount of time.
Since Sylvain told me that the entry about nitrox was quite interesting despite myself not going too much into details, I thought that it could be interesting to carry on with some details about diving and along the way answer a couple of questions that non-divers often ask when given the chance. It could also at least allow some mindly meaningful content as a support to pictures.
What most people are wondering very often, is the how deep divers are supposed to go. There is not a single answer to that question, but to make it quite clear. Recreational diving is happening mostly above 30m.
As I mentioned already, the air is made of roughly 78% of nitrogen and 21% oygen. This is what we get at the normal atmospheric pressure at 1 bar. When you are diving, you get an additional 1 bar of pressure every 10m. So at 10m you have 2bar, 20m/3bar, 30m/4bar and so on…
If we increase the pressure, we increase the amount of gas absorbed. So if we are diving at 30m, with 4 times the pressure, we will absorb 4 times the amount of nitrogen. Unlike oxygen, the body does not use nitrogen, so the gas accumulates in the tissues in time. It’s not an instant process though. The gas exchange in our bodies happens in our lungs with each breath and the excess gas is then carried to our body tissues by our circulatory system.
When you have all this nitrogen in your body and the pressure decrease (ie you are slowly going up (the slowly here is important, as I said already, it is not an instant process), the excess nitrogen is slowly eliminated by the body as we breath out the nitrogen.
If you come up to the surface without having eliminated most nitrogen, like for example diving 60mins at 30m and come up to the surface quickly, you can be sure to get lots of bubbles in your blood and you will get a kind of soda-like effect within your body. It will cause you major pain, depending on gravity you will get irreversible damage and if not treated, death will certainly follow. This is what is called DCS (Decompression sickness). If symptoms appear, besides immediately breathing pure oxygen, you must go to the nearest recompression chamber facility (hyperbaric unit).
One should keep in mind that there is no single and simple rule to avoid DCS. Some people got it diving in very shallow waters with no particular risk exposure known.
Several mathematical models exist to help in knowing the limits, they have been mostly based on experience and statistics, but in fact very little is still known. Most statistics have been obtained from army experiments and of course were done on very fit young individuals. This is one of the reasons why it is advised to keep reasonably fit and healthy.
The most famous work was done by John Haldane for the Royal Navy in the early 1900′s, otherwise a large amount of information has been gathered in the last decades by the US Navy and offshore diving companies such as COMEX.
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I had the invitation email since December 13, but it’s now official. I’ve been elected as a member of the Apache Software Foundation. I was very surprised (which is maybe a reason why on that morning I closed the door of my apartment with keys inside), but most of all I feel very proud and honored.
I think I’m an ASF committer since 2001 and an Ant PMC member since … later on.. but I will have to dig out details one day.
Many thanks to all of you, existing members, who sent me congratulation emails and thanks also to those who decided to nominate me.
Got my PADI Nitrox certification today. For the J2EE inclined, it has nothing to do with the NitroX IDE from m7 (now BEA) but is related to the mixture of NITrogen and OXygen. As you know already quite well, the air we breath is made of roughly 78.05% nitrogen + 20.95% oxygen + 1% trace gases including; carbon dioxide, carbon monoxide and various inert gases – mainly argon. YMMV vary if you breath air in the Cairo traffic. (You’ll avoid too much carbon dioxyde in your tank when diving unless you want to kill yourself quickly).
So air technically is nitrox.
What is meant by nitrox in recreational diving is an hyperoxic mix, that is, it contains more than 21% oxygen. The term used for nitrox in the diving industry is enriched air, enriched air nitrox (EAN or EANx). The most often used blends are 32% (EANx32) and 36% (EANx36) of oxygen.
What’s the deal with diving nitrox rather than air ?
Enriched air reduces the level of absorbed nitrogen in your body tissues, so it translates by longer no decompression limits, shorter surface intervals, longer subsequent dives, etc…. You get the picture.
It does come at a price though. The maximum operating depth is shallower and the risk of acute/central nervous system oxygen toxicity is much greater. Compared to nitrogen narcosis (which is your primary concern when planning a dive with air as oxygen toxicity comes into the picture at around 66m while recreational diving is normally above 40m), the problem with oxygen is that you may get little or no warning of an attack and your chances of surviving one are remote.
But lets’ not get to dramatic, that should not happen with proper planning. If you intend to dive at 28m with EANx36, you must stick to it and not go to 45m because you saw a hammerhead shark. You’ll maybe see the shark but probably not come back to tell anyone about it.
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‘Lighthouse’ is a special place to me. Not only it is right in Assalah Bay, meaning that virtually you can jump into it from most restaurants and dive centers but it also boasts a splendid marine life right from a depth of 3 meters. You can snorkel just right here and see most of the interesting marine life, either fish or nice coral, that I haven’t been able to see so close to the shore in any place I went with the exception of New Caledonia, and particulary on the island of Ouvea where you could even see small white tip sharks swimming effortlessly in 1m of water.
This is also normally a very good place for macro photographers, though some critters seems to have vanished a bit since my last visit. I tried to enquire about seagrass ghost pipefish (which is certainly one of the most difficult find). I will try to figure out within the next few weeks if there are still Red Sea Walkman and Sea Moth around here.
I have been diving this one on the lighthouse with Anthony, a civil engineer doing contracting work on ships but otherwise scouting the planet for dive sites, he virtually went everywhere. He was working last year in Utila (Honduras) and gave me some good tips, which will certainly be useful considering it is my next destination.
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