Safe Diving Practices E
| Emergency bale out plans (Tech. diving) |
| Equivalent narcotic depth (Tech. diving) |
| Explosives |
Emergency bale out plans (Technical diving)
If a diver loses his travel or decompression gases due to any of a number of reasons (equipment failure, gas loss, etc), the decompression schedule may become very punitive. This is especially true of ineffective off gassing of helium. The decompression schedule would become very long and the diver may not have enough gas to finish the dive or, in Northern European waters, may not able to cope with the cold conditions.
It is vital that back up gases are available to avoid this situation. All divers must plan decompression schedules to cover all potential gas failure possibilities and how they can set up spare cylinders in case they need them. These include:-
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Written or pre-programmed decompression schedules for longer bottom time than planned.
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Written or pre-programmed decompression schedules if the diver is unable to use travel or decompression gases in case of a gas loss or equipment failure.
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Spare decompression gas available to the diver in case of a gas loss or equipment failure.
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How the divers would access the spare gas in an emergency (spare cylinders on decompression line or cylinders lowered to divers from diving platform).
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Overall duration of emergency decompression considered relative to the expected water temperature.
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A diver to surface signalling protocol to facilitate requesting gas or assistance in an emergency.
Equivalent narcotic depth (Technical diving)
Equivalent narcotic depth (END) is the depth at which the partial pressure of nitrogen in the gas mixture would be the same if the diver were using air. The BSAC recommend a suitable END with regard to the dive conditions and a personal narcotic tolerance. One of the major benefits of diving mixed gas is to have a clear head whilst at the maximum depth. 30 metres is generally accepted as a narcosis level a diver can cope with in an emergency situation. Some divers are happy to increase this depth if the diving conditions are better, such as warmer water, better visibility, etc.
Explosives
It is extremely dangerous to attempt to recover or retain live explosive devices. Immersion in water could render them very unstable, especially if they are consequently dried out, so keep well clear of any such devices you find. If you consider that they are in a dangerous location, inform the Maritime and Coastguard Agency (MCA).
Never:-
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Attempt to bring them to the surface and on no account abandon them in shallow water, or on the beach.
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Undertake the use of underwater explosives for carrying out underwater work without a recognised course of training.
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Dive near sites where underwater explosives are being used since the shock waves can be fatal.
Page last modified: 11th Dec 2006 - 13:59:28