Dr Pyle began to meticulously record in great detail the events of every dive he was doing. After collating the data and studying it, he came to one stunning conclusion: the dives that resulted in less fatigue were the ones he collected a fish sample on.
Dives where he did not collect a sample were the dives that made him feel fatigued post dive. After all, he was an experienced scientist who had collected hundreds if not thousands of specimens, he was not a giddy new researcher happy with a fish.
He would have to dig deeper to find out the truth. After going back and looking at the data again the enterprising doctor finally had his eureka moment. He realized it was nothing to do with psychology, and had everything to do with exploding fish. Fish have a unique way of controlling their buoyancy; inside the fish, there is a swim bladder that the fish uses like a BCD.
The fish adds and removes gas from this bladder to control its buoyancy. If the diver does not do this, the swim bladder will explode on ascent and ruin the sample, and this is exactly what Dr Pyle was doing every time he collected a sample. He realized that these stops, which were much deeper than his normal decompression stops, not only allowed the doctor to bleed out gas from the fish, but also allowed his own body to release small amounts of gas from his fast tissues.
Thus preventing the formation of micro bubbles later in the dive or post ascent. The doctor went on to publish his findings and develop a mathematical formula for calculating his way of doing deep stops, and from that day on Pyle stops and deep stops were born.
Needless to say, since those heady days there has been more and more research as divers have taken a keen interest in developing this new branch of decompression theory.
Find out more about decompression theory. Khao Lak Liveaboards Similan islands Thailand. Not necessarily, but they are a good idea, any recreational diver worth his salt does a 3-minute safety stop at 5 metres after almost every dive, why? To allow their tissues to off gas and reduce the risk of bubbles forming after surfacing. It is exactly the same with using deep stops when recreational diving.
The stop also allows you to check that your gear is secure for exiting and fine-tune your buoyancy for that final ascent to the surface. During the stop, have just enough air in the buoyancy compensator BC to keep yourself neutrally buoyant and able to maintain a constant depth by varying lung volume.
As you begin the final ascent, any air in the BC will expand significantly; unless vented this may cause your buoyancy to become excessively positive. The following procedure applies to any safety stop, no matter the depth. Always make sure to monitor your air supply to ensure that you have plenty of air remaining to perform a safety stop or stops.
Ascents should be made as a buddy team. At least one buddy should monitor ascent rate and depth and both need to keep an eye on their remaining air supply. Both also should be poised to vent expanding air from the BC. As you near the desired stop depth, establish neutral buoyancy. In most cases this means venting air from the BC. However, be prepared to add a touch of air if you vent too much and begin to sink.
The goal is to have the right amount of air in the BC to maintain neutral buoyancy and then make minor adjustment by varying lung volume. Even though you are neutrally buoyant, still keep a close eye on your depth gauge. At the shallow depth of feet, even the slightest increase in lung volume can cause you to begin floating toward the surface without even noticing. When this happens, whatever air remains in your BC will expand, intensifying the situation even more.
A safety stop can be performed in either a vertical or horizontal position. To best consider all these variables, today computers are used to determine and plan the best gases and the dive schedule, plus emergency alternatives to handle reasonably possible problem situations.
Enriched air nitrox and pure oxygen are used during decompression because they accelerate how fast dissolved gas leaves the body. The diver switches between these during ascent, or, when using a closed circuit rebreather, changes the gas ratios during ascent. Each gas mix has a limit on how deep and how shallow it can be breathed safely, and decompression time increases disproportionately with depth, so that for dives deeper than feet, often decompression is longer than the time spent at depth.
The dive plan must therefore include how much of each gas is needed, where and when it's used, backup gas and equipment for emergencies, and how much of all this the diver can reasonably manage.
If you exceed a no stop limit and surface without making the required stop or stops, your risk of decompression sickness is considered unacceptably high.
How high? It depends. Any dive has some risk of decompression sickness because people vary in their physiologies and susceptibility. No computer or table can guarantee decompression sickness will never occur, even within its limits. Choose a dive computer intended for technical decompression diving. It should be capable of using several different gas mixes on the same dive.
An important point is that you need not one, but two compatible dive computers for this type of diving. While dive computers are highly reliable, you would not want to be stuck without your decompression info if there were a malfunction, so standard practice is to dive with two, staying within the limits of the most conservative even identical computers will vary slightly throughout a dive. What should I do if I miss the stop?
Assuming this happens by accident on a no stop recreational dive, ascend to 15 feet or deeper if specified by your computer and stay there until it "clears," meaning you have stayed the required stop time. Most computers show you the time as it counts down. For a recreational "oops" situation, the time would typically be short with only one stop required. However, you may be low on gas, so do not run out of gas underwater. Stay as long as you can, but if you don't have enough air to do the stop or you miss it altogether , surface with enough air to ascend at a proper rate and exit the water.
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