| March 2002 | Bottom Time | |
| SECTION 1 Using Air SECTION
2 SECTION 3 |
A winter diver (Lt. Eric Hahn of the Boston Police Department Dive Team) properly equipped with a Viking Drysuit and EXO-26 fullface mask with communications Using Air Are you dissatisfied with how much air you use?? My personal opinion is that most people worry way too much about this issue. That said, it would be helpful to know if this concern is recent or has been one for most of the individual’s diving career. As one gets older (and consequently less aerobically fit) one will use more air for the same dive profile they did several years ago. Even if one stays fit, the body will still inevitably become less aerobically efficient as it ages. Look at when you use more air. Are you physically or psychologically stressed before or during that dive? Do you use more air only when you have not been diving for a long while, or does it seem to be related to diving conditions, stress, or exertion? _______________________________________________________________________________________Freedom will be defended. Whether we bring our enemies to justice or justice to our enemies…justice will be done! President George Bush _______________________________________________________________________________________________________
Many divers very often ignore their pre-dive psychological state and fail to recognize what a huge difference it makes in any stress-inducing activity like diving. Often the difference between you and your diving partners is simply a matter of lung volume. The fullback and the ballerina are not going to draw in the same amounts of air to fill their lungs. The fullback will use more air, even if he is in better physical shape than the petite female. The only real difference that can be made will be to monitor your own stress levels and never dive if you are anxious. Once in the water, spend a couple of minutes on the bottom regulating your breathing rate and then continue with your dive.
Your Health and Diving What you don’t know…can hurt you Equalizing your ears can be a problem, especially after several dives in one day. Multi-day, multi-dive scenarios (like vacations) can raise havoc with your ears. It is important that you begin with the first dive of the day, taking special care to equalize early and often. Once even a small amount of barotrauma occurs, equalizing becomes much more difficult. Even worse, repeated and forceful attempts at equalization can cause a ruptured eardrum or other serious ear problems. Try descending feet first, gently clearing your ears as soon as they dip below the surface. Remember that the biggest pressure change is in the first 20 feet or so, so this is where you want to pay the most attention. Watch your buoyancy and let your buddy know that you’ll be taking your time. If possible, on a dive trip, be the first in the water, so that by the time the others catch up to you on the bottom, you be comfortable, and your ears will be too. Dive safe! n Questions and Answers Re: Tanks Q: Are all tanks the same? A: Absolutely not. There are steel, aluminum, and even titanium tanks. They come in all sizes and pressures. Q: What is pressure"? A: It is simply defined as a force exerted against an opposing body. For example, the gas molecules exert a pressure against the opposing force of the tank walls. Q: What are the variables? A: How many and what type of gas molecules are present, the amount of heat energy acting upon them, and the amount of the space available to them (the volume of the tank). Q: What is a "hot fill"? A: Hot fills result from a tank that is being filled too quickly, raising the temperature of the tank. That leads to a false reading of pressure on the high side.Q: What are the two most important measures of a tank? A: It is the combination of pressure and the physical dimensions of a tank that determine the tank’s capacity Q: Which tank material is better? A: Both have advantages and disadvantages. Steel tanks are more negative and therefore you need less weight on your belt. But they are heavier to carry. Aluminum cylinders tend to be less expensive and lighter, also less negative, therefore you will need more weight for the end of the dive. Both are susceptible to degradation, steel to rusting and aluminum to corrosion. Q: Give an example of cylinder comparison. A: A short steel cylinder that holds 100 cubic feet of air at 3500 psi is a bigger tank in terms of capacity that an aluminum 80 cubic foot tank that holds less than 80 cubic feet of air at 3000 psi. Even though the aluminum tank looks bigger, it is not.
|