Diving for Dummies
Trip Start Mar 17, 2007
450Trip End Ongoing
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Well, in the countries we normally dive in, we wear a t-shirt (or not), a mask, fins and a BCD with 'stuff'.
Masks and fins, you can imagine. The BCD is (if I recall correctly: an abbreviation of Buoyancy Control Device) is a 'coat' you wear in which you can pump air. Depending on the air you pump in there, you can float where ever you want, on the surface or many meters deep, or go deeper or shallower. It has to contain just the right amount of air to keep you on the level you want to be. If you dive at 30 meters (the maximum depth a recreational diver can go) and you want to stay there for let's say 10 minutes, you have to be 'neutrally buoyant' and pump the perfect amount of air in your BCD.
Connected to you BCD is your tank of air, your regulator, your octopus and your gauge.
Left arm: your gauge: this equipment tells you how much air you have left in your tank. Mind you: it is compressed air NOT oxygen. If a person would breathe pure oxygen, they would die. You begin your dive with more than 300 atmospheres of compressed air. The amount of air you are using depends on the depth you are diving at and your experience. At 30 meters it will be 20 to 30 minutes. For shallow dives and experience divers it can be as much as 2 hours. YOUR TANK SHOULD ALWAYS CONTAIN AT LEAST 50 ATMOSPHERES OF AIR, for safety and also because you might (will?) need a safety stop, but I'll explain about this later.
Right arm: you have your regulator, this is the tube you put in your mouth to breathe through and your octopus, this is your spare regulator. This one is used for emergency for yourself (if your regulator does not work) of to help someone else (if they are out of air and you have plenty).
We are diving in WARM water: above 25 degrees. If it is less, we need a wetsuit. The standard wetsuit for above 20 degrees is a 3 millimeter wet suit. That is a suit, 3 millimeters thick, which lets water in. The water in your wet suit is a very thin layer and is warmed up by your body in seconds and stays there, keeping your body (fairly) warm. Dry suits also exist for really cold water: they do not let any water in, like a good rain suit. But, we never dive in such cold water. My maximum time at 25 degrees with a 3mm wetsuit is 1 hour, Dr T could do 2 hours, I think. One of the many rules of diving: when you are cold: STOP diving. When I am really cold I give the 'thumbs up' to my partner and poor thing has to come up with me.
You know about the gear now, we can start diving. Normally there is a briefing upfront, which is given by the diving master and we dive behind him/her. In the briefing the important signs are repeated. Like I told you on the Jules Verne dive, Dr T gave me the danger signs. There are hundreds of signs (a bit like a deaf language) but you only have to know a dozen to dive.
You ALWAYS buddy up. This means you have a partner, who checks your gear and looks after you all the time. I promised to tell you about the danger of diving and why people rarely die. The main reason: they dive on their own. Many, many things can go wrong down there, of which I think, 99 percent can be solved by your buddy. You stay together, keep an eye on each other, help one another and if you are confident enough, point the nice things out to each other. We are still not in the water. The first person gets ready, gear checked by themselves and their buddy, blows up their BCD (to float), jumps and gives the 'I am OK' sign to the boat. Second one jumps. Normally you both wait for the diving master but sometimes, experience divers do not have to.
Let me go on with hubby and me. We did about 120 dives together, so we know each other pretty well. We rinse our masks and give the 'thumbs down' sign, which means: we are going down. Going down is the most difficult part of the diving, I think. On earth we have a pressure of 1 atmosphere. If not we would walk like the people on the moon, where the pressure is almost zero. Going down in water, means your pressure is going up, by 1 atmosphere per 10 meters. This means that the first 10 meters, the pressure on your body doubles!!! The next 10m meters it is only 1/3 more and the difference is getting smaller and smaller as you get deeper. This, however, does major things to your body. Every time I dive I thank those people (and animals) who sacrificed their life, so diving became safe.
Two major things are happening:
1. Your air chambers in your body (lungs, sinuses, ears,...) get compressed. If you would take a nice, big, red, firm tomato in your hand and dive to 30 meters, it would be squeezed, like by a giant hand, closing on it firmly. Having your airbags in your body squeezed is very painful, believe me. You have to equalize them, by putting more air in them.
2. Nitrogen gets in your body. This is the dangerous part. You do not feel it and it is lethal!!! Staying too deep, too long, makes little bubbles in your blood. Your veins are changing into sparkling water! And those sparkles go to your head and heart and it is often fatal.
If you go deep and long, you have to let the nitrogen out of your body before surfacing. If you don't, you have to go into a decompression chamber, for hours or days, a chamber designed to clear your veins from bubbles. Decompression chambers are rare and unbelievable expensive. You pay or die. Luckily, this should not happen. This is why we have 'safety stops'. Coming up, we stop for a certain number of minutes at a certain depth and that takes out the bubbles in our blood. For 30 meters, 20 minutes, a safety stop of 3 minutes at 5 meters is normal. You just 'hang' there, waiting for the nitrogen to leave your body.
My hubby, and very experienced diving masters, can do this 'hanging' there, without moving anything, not even a finger. I compare this to driving: try to drive a straight road, without changing your steering wheel 1 millimeter. I cannot. Can you? If I have to be neutral buoyant, I go up and down like a yoyo, only 50cm, but still.
For 2 years, we have diving computers, we both have and this changed our whole way of diving. Normally a diving master is holy: you obey him or her. I do, but not if my computer tells me it is not safe. And I tell them upfront that I obey my computer and they respect it. More: like in Jamaica, where we dove for 4 holidays already, they count on our computers. But, whether they like it or not, if my computer says: enough, I give my buddy (and the diving master if there is one) a 'thumbs up' and I go to the surface.
A couple of years ago, we dove the 'Thistlegorm' in Egypt. A war ship which sunk with everything on board. A diver's orgasm. Tanks, motorbikes, weapons, boots, ... . But it is 40 meters under water. We stayed for 40 minutes. Not having any dive computers, we did not know better, but the fact was, I ran out of air. No, not below 50 atmospheres, out of air, no more breathing. And we needed a safety stop of 20 minutes, me sucking the air from Tony.
We don't do these things anymore. We have a lot of experience and a perfect diving computer. When I decide I go up, nothing can stop me. And my buddy is professional enough to come with me. We follow the PADI rules (PADI is known all over the world for being the best diving school), we are both experienced, Dr T has much more dives and I have a Rescue diver certificate, which is just under the diving master. We trust on our computers and our experience and then I really think diving is a safe sport.
When is it not safe? If you dive on your own. If you do not follow the rules (plan your dive and dive your plan). If you ignore your computer. If you take risks. If you dive with a buddy you are not used to. If you dive with a company that cannot be trusted (not PADI certificate). We do not. Diving is safe. You will not break a leg nor have muscles hurt. You can die. But only if you are foolish. And we are not. So: little brother, do not worry: your baby sister knows how to dive.
I probably bored everybody, the divers for sure. And my hubby did not get to his laptop all night. But I thought you ought to know.