Safe Diving Practices N
| Neutral buoyancy |
| Night diving |
| Nitrogen narcosis |
| Nitrox |
| No clear surface |
Neutral buoyancy
Neutral buoyancy is achieved when the diver is able to remain in either a static position in the water when using a rebreather or rises or falls about a static position as a result of breathing in and out when using open circuit equipment. Comfortable diving means the achievement of neutral buoyancy, if required, at any stage of the dive. Correct weighting is critical to gaining neutral buoyancy easily; the diver should carry just enough weight to hold a 6m decompression stop with a nearly empty cylinder.
The NDC strongly recommend that, where a drysuit is being worn, the drysuit is used to maintain neutral buoyancy underwater.
Night diving
Night diving, especially in tidal waters, requires very careful planning. Each diver should have a working torch otherwise the dive should be terminated. Each diver should carry a backup torch or some other means of identifying their position if their main torch fails. An efficient system of marking the point of exit must be employed. Care must be taken with diver to diver signals to ensure that the torch is not shone directly into the diver's eyes.
Nitrogen narcosis
As the partial pressure of nitrogen in a diver’s breathing gas increases with depth it begins to have a narcotic effect on the diver. Nitrogen narcosis decreases a person's ability to cope with emergencies, slows down reaction and realisation time and increases the risk of an accident.
Nitrox
The use of nitrox (nitrogen / oxygen mixtures where the oxygen content is greater than that of air) as a breathing gas can provide a safety benefit in terms of a reduced risk of decompression illness, or enable longer dive times / shorter decompression stop requirements with no added risk. The use of nitrox has certain disadvantages which require training and suitable equipment to minimise the risk.
Properly trained and qualified BSAC members are permitted to use nitrox on branch dives, with the approval of the Dive Manager. The BSAC provides a range of courses and qualifications in nitrox diving.
The BSAC recommends a maximum partial pressure for oxygen exposure when diving of 1.4 bar. For divers with additional appropriate qualifications a maximum partial pressure of oxygen for decompression of 1.6 bar is recommended. This figure will determine the maximum operating depth for any nitrox mixture. Failure to observe the maximum operating depth for any gas mixture may have fatal consequences due to the onset of oxygen toxicity.
No clear surface
(Cave diving, ice diving, diving inside wrecks).
Members wishing to dive in caves should contact the appropriate cave diving organisations, as this is very specialised diving, in terms of technique and equipment, and is not covered in BSAC diver training.
Diving under ice should only be undertaken with a surface party of at least two. This allows one to tender the divers, while the other is free, if required for any other reason, including an emergency. One of the divers must be securely roped to the surface, if diving in pairs, and contact between them should be by means of a buddy line.
Wrecks should not be penetrated without proper training and equipment.
(See Wreck diving)
Page last modified: 18th Dec 2006 - 11:35:57