Decompression Diving – What exactly is it?
When a diver gets their basic diving or open water certification, they learn all about no decompression limit diving. While a safety stop at 3 m for 3 minutes is recommended, this technically is not a decompression stop. It is designed to add extra safety into the dive for recreational divers.
Recreational divers with their open water certification are not trained for decompression diving. The primary reason is that the time required for deep dives with long bottom times and decompression stops exceeds the one air tank that recreational divers are trained to use.
Decompression diving includes a mandatory stop at a specified depth for a specified time (ranging from 1-15 min). There can be multiple decompression stops on an ascent depending on the total bottom time. Certifying organizations like PADI even introduce this concept to their recreational divers recommending that any dive over 30m have a half stop of at least 1 minute.
A half stop is a safety stop at half the maximum depth. If you dove a 30m dive, you would stop at 15m for one minute and then again at 5m for 3 minutes. The stops at varying depths are there to help your body get rid of excess nitrogen.
While no open water certified diver who dives under the no decompression limit bottom time is required to make a safety stop or a half stop, it is recommended to put these practices into use. This will make sure your body can off gas the nitrogen that has built up in your bloodstream. Keep in mind that just because you are diving under a no decompression bottom time limit doesn’t mean you are immune to decompression injuries and illness.
Should You Avoid Decompression Stop Diving?
Only divers who been trained in decompression stop diving should dive this way. Decompression stop diving changes your total length of time in your ascent. Because an open water certification teaches you that you can get to the surface relatively quickly, most open water certified divers are not prepared for the length of time it takes to surface on a decompression stop. This means on a decompression dive a diver risks of running out of air if they are not properly prepared.
Organizations like SSI and PADI both offer training for divers who want to dive decompression stop bottom times. It is recommended that anyone who wants to experience this technical side of diving go through the training to avoid any risk of injury or death.
What to do when your dive computer warns you of a decompression violation?
If you’re diving and your dive computer starts to alarm you about a decompression violation, you should descend back to the decompression stop depth and wait the appropriate time. This is under the assumption that you have enough air to do the decompression stops that the computer is requesting. If you are low on air, your options are limited as to what you can do for a decompression violation.
Most dive computers will shut down for a maximum of 24-48 hours if you have violated the decompression stop. This is to ensure that you have a surface time of at least 24 hours. That full day of surface time gives your body the opportunity to off gas any excess nitrogen assuming you have not experienced decompression sickness.
PADI trains divers on emergency decompression protocols. Under their training, they recommend that if it ever exceeds the new decompression limit by up to five-minutes, they make an eight-minute decompression stop at 3 m and then not dive for six hours. If they exceed the decompression limit by more than five-minutes than they need to make a 15-minute stop at 3 m and not dive for at least 24 hours.
It is always wise to consult your dive tables before diving multiple times, even if you have a dive computer. This is so you can make sure you know your maximum bottom time and your excess nitrogen levels. Knowing this without the aid of your computer can ensure that if your computer fails you still don’t put yourself in danger. Remember always round up when estimating bottom time.
How to practice decompression diving?
To practice decompression diving, you need two dive computers. You will want to change one of the dive computers to the “very conservative” setting and leave the other dive computer is set to the “normal” settings. Dive within the maximum depth that your certification allows you.
You will want to let the very conservative setting dive computer going to decompression mode. Your normal setting computer should not have exceeded the no decompression limit dive time at this point. You will follow the decompression stop limits set by the very conservative computer to practice a decompression dive.
Anytime you’re practicing in decompression dive you should always be under the supervision of a trained diving professional or dive instructor. This will help ensure that if anything goes wrong, you have expertise available to help guide you through the new experience. Having a diving instructor with you while you practice decompression diving will also give you the confidence you need to execute the decompression stops correctly.
Remember not to try decompression stop diving without an instructor or certification on hand. Decompression stop diving takes extensive experience. Your safety and life are more important than extra bottom time. With that in mind keep on diving and enjoy your no decompression limit dives.