Safety stop on Tafelberg Reef

Decompression diving

Safety stop on Tafelberg Reef
Safety stop on Tafelberg Reef

As a rule recreational diving is no decompression diving. The dive tables are designed to ensure a huge safety margin and you could ascend directly to the surface (no faster than 18 metres per minute) and in theory you should not get bent. Safety stops are just that: a stop, usually at 5 metres for a minimum of three minutes to allow your body to eliminate some of the nitrogen it has absorbed while you were at depth.

So what if you go into deco?

Should you exceed your maximum bottom time there are a few basics and that is where decompression comes in. A regular safety stop is a deco stop and three minutes is considered adequate on most dive planning, but for example a Deep Specialty calls for a simulated deco stop of 8 minutes with some of this time spent breathing from an alternate air source.

By the time a diver gets to this level of training they invariably have their own dive computer and your dive computer will show you that you have exceeded your bottom time and now have a decompression commitment – usually an eight minute safety stop.

When we do these dives we dive on enriched air/Nitrox and leave at least one of our dive computers on air. The result is that the computer set on air will give you a warning that you are now in deco and it will indicate the length of your required safety stop and the recommended depth. Providing you have planned your air consumption and air supply correctly you will be able to fullfill the deco commitment and surface with your computer ready for  another dive.

Failure to complete the required safety stop for the entire recommended duration your computer will normally not go into full dive mode until 24 hours have passed. By doing the dive on Nitrox yet leaving your computer on air you give yourself  a safety margin, allowing you  to experience the actual computer output screen and interpret what it is wanting you to do, without the risk to your health of actually going into deco and being unable to fulfil that commitment for some reason.

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Tony

Scuba diver, teacher, gadget man, racing driver, boat skipper, photographer, and collector of stray animals

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