Decompression Diving

Decompression Diving

As we become more adventurous, whilst diving do we ever think to know what lies deeper, or do we have the thought: “I wish I could spend more time on the bottom”, a lot of people ask, why would I want to dive to 40 meters if I can only stay there for 9 minutes, when It comes to decompression a lot of people shiver at the mention of it, but that’s because most divers don’t understand it, in this blog we Jump into the detail of decompression and its advantages.

What is Decompression Diving? 

Decompression diving or deco diving means intentionally going beyond no Decompression limits to achieve a longer bottom time at a given depth. Depending on your dives objectives this could mean spending an hour at 30m or 20 minutes at 50m. 

Going beyond your dive computers NDL’s gives you freedom to do more on a dive, Perhaps you would like to explore the entire Um el Faroud on a single dive, for those who know this spectacular wreck, she lays on the bottom at a max 36m and stretches out to 110m In length, so can we explore this whole wreck on recreational tables? The answer is quite simple, and with Decompression diving this is just an example of what is possible to explore when doing deco diving. 

Decompression diving can help you achieve both the bottom times and depths you seek. 

Physiological Aspects

As you descend during a dive, the nitrogen you are inhaling dissolves into your body tissues, like sugar into a cup of tea. When you spend time at depths gas enters the bloodstream through your lungs, then via the blood it dissolves when entering the different tissues of the body.

When you ascend the absorbed nitrogen then leaves the tissues and is transported away back to the lungs where eventually you exhale it out This whole process is known as “on gassing” and “off Gassing.”

How much and how fast you “On” and “Off” gas depends on multiple factors. These includes the percentage of nitrogen you breathe ,how deep you go , how long you spend at depth, which type of body tissue, how hydrated the body is, fitness of the diver , how warm you are ,and how fast you descend and ascend and which Gases you breathe.

Every tissue has a different on-gassing and off-gassing rate, Decompression diving involves on-gassing more nitrogen, which means a diver must make a series of stops during his/her ascent. So as we ascend from a decompression dive our stops at different depths have certain times at each stop, this varies 

depending on your dive plan and profile, it will also be different if you are breathing a certain gas to help speed up the processes of eliminating absorbed nitrogen.  The crude analogy would be the difference between opening a bottle of coke quickly and creating lots of bubbles or opening it gradually and allowing gas to escape in a controlled way.  

Risk and Management Planning


As for any dive Recreational or Technical, it should always be planned, the most important thing is to check your dive equipment and gas before the dive, if you know that all your equipment works and the gas you have for the dive is adequate you have already started off on a good note. When doing decompression diving, most of the time we spend at depth, which means we need more gas, as 

when we dive deeper our air consumption increases because of pressure. When doing a Decompression dive Tech Divers are usually fully prepared for such a dive, with twin sets or rebreathers and different gasses in extra cylinders they carry with them. In each cylinder, there might be a different gas to help with the off gassing on an accent, and breathable gas on a decent to the planned depth, when doing a decompression dive you usually plan the dive the day before, to assure that the right gases are acquired for the dive. 

Tec divers also practice emergency procedures until we can undertake them to a very high standard. We decide on our dive’s objective and then decide on a dive leader. Tasks are split between team members so that no one is overloaded.

The Adventure

Without training and practice,these considerations can seem a little overwhelming. But once you’re qualified and have had plenty of practice, the rewards can be never ending. Longer bottom times

 mean you never know what you might see or find. You may enjoy spending a long time inside a wreck or cave. Or, you may get great satisfaction from undertaking a series of small, chronological tasks during the dive to achieve a safe outcome. Either way, decompression diving introduces a whole new world underwater.

And no it’s not scary, as John Kendal GUE guru says: “My main thought about deco is that it is something you need to do. Sometimes it’s not a lot, sometimes it’s a lot, but if you don’t do what you need to do then it can hurt.” 

For more information check out IANTD Advanced Nitrox Diver and PADI Tec 40

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