Dive Training
So you’re thinking about trying scuba diving, but you’re not sure where to start. It is actually not difficult to get your entry-level certification to dive, easier than getting a driver’s license. Look in the Yellow Pages or in the Directories section of this website for a shop near you, or inquire at the local college, university, or YMCA, which may run classes that are open to the public.
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Moving on to the professional level, the lowest professional rating is Divemaster. I would hardly recommend doing this unless you are really interested in turning Pro - Divemaster is the longest and most arduous rating of all to get. The Divemaster course is like graduate school - a year or more of indentured servitude. On the other hand, pitching in with classes and other activities can be a lot of fun. Divemasters are the sergeants and mules of the diving world and carry out much of the tour-guiding, tank-filling, and grunt work at resorts and on dive boats. Beyond Divemaster, there is Assistant Instructor, which is basically gold-plated Divemaster, and then increasing levels of Instructor.
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An Explanation of Professor A.A. Buhlmann's ZH-L16 Algorithm
by Paul Chapman
Note to new divers and potential new divers:
This information is presented for general interest. Don't be scared off by what you see here - you don't need to learn any of this to become a safe and competent scuba diver. You will however need to understand dive planning.
The following is a summary of the decompression algorithm described by Dr A.A. Buhlmann in the fourth edition of his book Tauchmedizin ( diving medicine ) published in 1995 ( only in German. ) the book contains a considerable amount of other information and is published by Springer-Verlag ISBN 3-540-58970-8. Rumor has it that at the time of writing ( November 1999 ) an English translation is being prepared for publishing, so hopefully, in due course, this document will become redundant.
The algorithm is simply a "recipe" for modeling the behavior of inert gases, which diffuse in and out of our body tissues when breathed under varying pressures. The intention is that if the recipe models the actual processes in our bodies accurately enough, it can be used to plan dives ( and other pressure exposures ) with a view to avoiding decompression sickness.
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If Nitrox will not take you deeper than air, what will? I touched on a couple of possibilities previously - Trimix and Heliox, but I did not explain what they are, or how they work. I'm not a "Tech" diver; I'm not interested in going deep enough to actually need such gas mixes, and I've never taken a formal class in such things. But I do have an engineering degree, curiosity, and half a brain.
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"DIR" or "Doing It Right" is a system of diving developed by cave divers which involves extremely rigid gear configurations and methodologies. To its adherents, DIR takes on an almost religious significance. For the true follower of DIR, no deviation may be tolerated, because DIR is perfection.
DIR is designed for cave diving. The usual object of cave diving is to go in and come back out alive. In line with this goal of accomplishing essentially nothing, DIR espouses an absolutely minimal equipment kit: "When in doubt, leave it home." DIR also espouses teamwork, mutual interdependence, and close lock-step buddy diving, things that are pretty much unavoidable in the confines of a cave anyway.
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Here is a description of recreational dive planning. The purpose here is to demonstrate basic dive planning and use of Dive Tables for non-divers who are interested in becoming certified but are worried about the complexities and math involved. Learning to use dive tables is usually the single most daunting classroom task for a student diver. It's really not all that hard.
The purpose of dive planning is to manage the Nitrogen gas that is absorbed into the tissues of your body while breathing air at higher-than-normal pressures underwater. If you absorb too much Nitrogen at depth and then ascend to normal atmospheric pressure, the gas will form bubbles in your blood and tissues. This is called Decompression Sickness, commonly known as "the bends." Decompression Sickness can vary in severity from barely noticeable to fatal, depending on your dive profile and other factors. The goal of no-decompression dive planning is to plan your dives in advance so that under no circumstances* can ascending to the surface result in Decompression Sickness.
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From way back when in 1996 ...
by Dr. Jolie Bookspan, author of Diving Physiology in Plain English
Myth 1 - The Dive Reflex Protects You
In the dive reflex, heart rate and limb blood flow decrease. Careful science ( that means we didn't accidentally step on the thermisters ) shows time and again that the dive reflex does not reduce the need for oxygen underwater as it does in marine mammals. Field studies ( where you're allowed to step on the thermisters ) indicate that the dive reflex does not extend breath-holding time. Occasional cases of human survival after very cold water near-drowning are not due to the dive reflex. Cold is the likely mechanism behind the reduced metabolism that permits survival.
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More important than gear is training, and more important than training is experience. You can buy gear and training, but there is only one way to get experience.
In aviation there is a saying: "You start out with a full bag of luck, and an empty bag of experience. The trick is to fill up the bag of experience before the bag of luck runs out." The same is true for diving. Take it slow. As one of my instructors said: "There are old divers, and there are bold divers, but there are no old bold divers."
When you start out in this sport, buying your first set of dive gear can be bewildering, not to mention expensive. The sad truth is that as a newly-certified diver, the equipment you have seen and used so far is not what you should be buying for real-world use. Almost all of it - jacket-style BC, weight belt, light, snorkel, etc - is more suited to floating students in a swimming pool or quarry than real-world diving. Most scuba gear is designed for the mass market of easy, infrequent, warm water diving, and is inadequate and/or inappropriate for diving around here. With so many different models and variations of everything - how do you select the best equipment for you? In the absence of any other guide, your first impulse may be to go out and buy just the same gear you were trained in - which is almost certainly an expensive mistake.
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