If you’re new to diving or if it has been some time since your last scuba adventure, you may be looking for more information about safety stops. A safety stop is a method for eliminating nitrogen from the body’s bloodstream and tissues to reduce the potential for decompression sickness. Here, we’ll take an in-depth look at safety stops and discuss their importance.
Why Make a Safety Stop?
Unfortunately, divers often skip safety stops because they feel they’re just not necessary. Nothing could be further from the truth. Since nitrogen accumulates in the bloodstream and tissues even during fairly shallow dives, the body needs a way to safely eliminate the excess nitrogen. With a safety stop, you eliminate excess nitrogen by allowing its pressure to remain higher than that of the surrounding environment; this ensures that the excess is processed out of the lung tissue and is exhaled along with spent breathing gas. Without a safety stop, your risk of developing DCS increases markedly.
Though most major training organizations teach divers to take safety stops lasting between 3 and 5 minutes at a depth of 15 to 20 feet, practices vary widely among certified divers – particularly those who dive on their own or with a buddy. Many feel that safety stops are not mandatory, and among those who prefer to take them on every dive, opinions vary as to what depth is best for effectiveness. In the past, experts recommended that recreational divers take a safety stop at a depth of ten feet; today, depths vary from one dive profile to the next. No matter what the depth, a three to five minute stop is the norm. If you’d like to be extra careful, you can take more than one stop. Studies have shown that a longer stop at a deeper depth, combined with a short stop closer to the surface is more effective at eliminating excess nitrogen than a single stop is.
Calculation of Safety Stop Depth According to Dive Profile
While a safety stop at the depth of ten feet is definitely better than nothing, you may find you feel best after diving – and enjoy less risk of DCS too – if you carefully calculate your safety stop depth. Don’t worry if math isn’t your best subject; this is a really simple calculation to make. Take your maximum depth and divide it by half. If the number you come up with is not a multiple of ten, round it to the nearest multiple of ten; i.e. if your number is 47, you would round it up to 50. Take your first safety stop at a depth of 50 feet, and stay there for two minutes. Ascend, taking one-minute safety stops every ten feet until you reach a depth of 20 feet. Once you reach 20 feet, conduct another safety stop, this time for a duration of two to five minutes, or even longer if desired. Slowly ascend, taking 30 seconds to make your through the final ten feet of your ascent. Making a very slow, controlled ascent in this manner might seem like overkill, but it is the best way to almost completely eliminate the potential for decompression sickness.
Safety Stops and High Altitude Diving
Some of the nicest dive sites in Europe and other areas are in high mountain lakes. If you plan to dive in lakes at altitudes of greater than 300 meters above sea level, your dives are to be considered as high altitude dives, and your depths and durations will be different from the dives you make at sea level. Atmospheric pressure at altitude is lower than it is at sea level, and fresh water has a lower density than salt water. Both of these factors combine to reduce the potential for decompression sickness; however that does not mean that safety stops should not be factored into your dive plan. Be sure to follow high altitude dive tables, and protect yourself further by ensuring that you wait for twelve hours after arrival at altitude before commencing a dive.
Shallow Dives and Safety Stops
If you’re like most divers, you rely on a dive computer that recommends you conduct a safety stop regardless of the maximum depth you attained while diving. For shallow dives in water ten meters deep or less, safety stops are not imperative, but taking them will certainly not harm you. In addition, avoid diving to shallow depths, surfacing without making a safety stop, and then diving again repeatedly. This will almost certainly lead to decompression sickness. If you are doing repeat dives, then be absolutely sure to take safety stops each time, and be sure that you ascend slowly, pausing for another few seconds when you reach a depth of three to four feet.
Technical Divers and Safety Stops
If you are planning to become a technical diver, you’ll discover that the depth and duration of your decompression stops will vary widely depending on the depth of your dives as well as on the type of breathing gas which you use. Most of the time, technical divers utilize deep stops as an added protection against the development of decompression sickness, and of course almost all rely heavily on dive computers for calculating safety stops appropriately.
It’s important to remember that your body will experience the greatest pressure change during your ascent through the last fifteen feet of water, so it is absolutely crucial to maintain buoyancy control. Taking a safety stop just before that final ascent will allow you to fine-tune your buoyancy and make a controlled ascent much easier to execute. You can also check your dive statistics against your dive plan during this time, ensuring that you have not exceeded the parameters of your planned dive. You can also use these moments to scan the surface for boat traffic and other hazards before making your final ascent, and if you’re at a scenic dive site, you can certainly use the time spent on your safety stop to take one last look at the beautiful environment you’ve just explored.