How deep can you dive before you have to decompress?
The depth at which you can get decompression sickness or the bends is more likely deeper than a dive to 5-6 metres (16-20 feet). But having said that, always take the same safety precautions no matter what the depth of your dive.
How deep can you dive before you have to decompress or at what depth you can get decompression sickness is likely to be deeper than 5-6 metres (16-20 feet). But this may depend on a number of other factors. These factors include the divers' bodily make up (i.e. whether or not they are obese). These factors also include diver fitness, including any medical conditions, such as a hole in the heart. But also hydration, hard exercise on the dive or afterwards and how cold the water is.
At what depth can you get decompression sickness?
In my opening sentience I use 5-6 metres (16-20 feet) as the cut-off for what depth you can get decompression sickness. But having said that, decompression sickness (DCS) is such a random event. Almost any dive profile can result in DCS. Just because you're diving at a shallow depth, don't let this fool you.
"Since DCI is a random event, almost any dive profile can result in DCI, no matter how safe it seems. The reason is that the risk factors, both known and unknown, can influence the probability of DCI in myriad ways. Because of this, evaluation of a diver for possible decompression illness must be made on a case-by-case basis by evaluating the diver's signs and symptoms and not just based on the dive profile."Divers Alert Network - Decompression Illness: What Is It and What Is The Treatment?
When I was a member of a BSCA club in Saffron Walden in the UK, a club member who had a Ventricular Septal Defect or a hole in the heart managed to get decompression sickness symptoms diving in just 10 metres (30 feet) of water.
The symptoms she suffered were mild and in fact was a skin bend. However, this proves that you can even get decompression sickness on shallow dives too.
Diver safety at all times
You are therefore advised to take the usual precautions, no matter what the depth and length of your dive. Dive to the appropriate dive tables or dive using your dive computer. Always ascend slowly, no matter whether you're diving to 10 metres (30 feet) or to 40 metres (131 feet).
The depth you get decompression sickness is affected by many factors
There are many risk factors associated with decompression sickness. Some are known, whereas others are unknown.
Because of this, the depth of dive at which the risk of getting decompression sickness must be evaluated on a diver by diver basis. This means that a diver's signs and symptoms of DCS may not just be based on the dive profile and depth of dive alone.
Whilst it's known that a rapid ascent from a dive is closely linked to decompression sickness, as well as missing decompression stops, there are other factors at play too.
These other factors include the following:
- Obesity and fitness of the diver concerned.
- Dehydration or how hydrated the diver is before the dive.
- Hard exercise immediately after surfacing from a dive.
- Hard exercise at depth.
- Pulmonary disease, including Ventricular Septal Defect or a hole in the heart.
- The length of the dive.
- How cold the water is.
Decompression stops on dives
The shallower the dive, the less there's going to be the chance of needing to carry out a decompression stop. On a dive to 10 metres (30 feet), you're more likely to run out of air well before you need to carryout a decompression stop.
However, the deeper the dive, the more chance of running out of no decompression stop time, as the need to do decompression stops increases with depth.
A diver at 6 metres (20 feet) may be able to dive for many hours without needing to do decompression stops. But in comparison, a diver at 40 metres (130 feet), has around 12 minutes on no decompression stop time according to the PADI dive tables.
The risk of decompression sickness increases with depth and length of dive. So when you're planning a deeper dive to more than 10 metres (30 feet), please bear this in mind. But as a further safety precaution, always carry out a safety stop at between 5-6 metres (16-20 feet) at then end of every dive.
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