Safe Diving Practices A
Access / Egress
Ensure that your access to the water is safe and that you can successfully regain contact with and recover onto your boat / beach / shore. Always ensure, when diving from the land, that it is possible to climb out at the planned exit point at varying states of the tide and under prevailing weather conditions.
Accidents / Incidents
Anyone involved in a diving accident or incident is encouraged to submit a report, in confidence, to BSAC for inclusion in the Annual Diving Incident Report. It is a requirement of BSAC membership that members involved in a diving accident or incident should notify BSAC HQ. An incident report (available from the BSAC HQ or the BSAC website) should be completed and returned as soon as possible. Reports are treated as strictly confidential and are used to prepare an analysis of safety performance each year, from which any emerging issues and their training implications can be identified, whilst protecting individuals’ anonymity. If there is any possibility of a third party insurance claim arising out of the circumstances it is particularly important that a form is completed without delay.
Adverse diving conditions
Divers should always consider the weather and sea conditions and ensure that their experience is adequate for the conditions anticipated. Due to the extra discipline and precision required when diving deeper or involved in wreck or cave penetration, adverse diving conditions should be avoided. Examples are heavy seas or strong tidal currents.
Air (gas) reserve
Always ensure you have an adequate reserve of gas (at least one third of cylinder(s) capacity is strongly recommended) at the termination of a dive. The amount of gas deemed to be an adequate 'reserve' will obviously depend on a number of factors including the size and working pressure of your main cylinder together with the depth and type of the dive - a standard figure is not appropriate. The reserve should be sufficient for a normal ascent, plus any decompression stops, allow adequate amounts for surface swimming and allow for the potential need for the buddy to use the diver’s alternate air source throughout the ascent. Remember that rates of gas consumption can vary enormously with the effects of cold, fitness, experience and depth, and you should monitor your own and your buddy's gas supply regularly.
Alternate (gas) sources (Air and nitrox diving)
The BSAC strongly recommends that all divers carry an Alternate (gas) Source (AS) in the event that they may need to share gas underwater.
Suitable AS include an 'Octopus Rig' (a second 2nd stage fitted to the same 1st stage of the regulator, which includes the type fitted to a direct feed). In this case divers should be aware that a first stage failure on their regulator will affect both second stages and may render them in-operative.
A more strongly recommended alternative, however, is a totally independent gas supply such as a 'Pony cylinder' (a small 2-7 litre auxiliary cylinder attached to the main cylinder with its own regulator assembly) or separate regulators attached to each cylinder of a matched pair. If a manifold is fitted to the pair of cylinders, making them into a 'twin-set', it should allow the diver the ability to isolate each cylinder / regulator assembly should a failure occur. Auxiliary cylinders having a capacity of less than 2 litres and BC mouthpieces are not considered adequate AS.
Alternate (gas) source / Bale out (Technical diving)
It is recommended that all technical divers should carry an alternative gas supply with its own regulator assembly, to provide the following:-
- An adequate bale out breathing system in the event that the diver’s primary supply suffers a catastrophic failure.
- A breathing system to support an assisted ascent to the surface in the event that their buddy’s breathing system suffers a catastrophic failure.
Divers should satisfy themselves that:-
- The system contains sufficient gas to provide for the above capabilities in addition to any planned gas consumption and any likely consumption due to changes in depth, mask clearing etc.
- The gas supply can be isolated in the event of a malfunction.
The capacity of an independent bale out system and the gas mix it contains should be adequate to enable an ascent to be made to the surface from any point during the dive, including any decompression requirements. It is recommended that the capacity allows a significant margin to cater for the significantly increased breathing rate inherent in the stress of a bale out. Incidents have indicated that a Respiratory Minute Volume (RMV) otherwise known as breathing rate (surface) of between 50 and 70 l/min is not unusual under the stress of a bale out situation. Ideally, the calculations should allow for one third of the bale out gas to be available on surfacing. It is the diver’s obligation to ensure that bale out is calculated in the dive planning process and gas is safely managed throughout the dive.
Altitude and reduced atmospheric pressure
Diving at altitude, or travelling to altitude (including flying), either before or after diving, involves the diver being exposed to a reduced atmospheric pressure. This can both affect the decompression procedures required and increase the diver's susceptibility to decompression illness. The BSAC 88 decompression Tables, Levels 1-4, (Air and nitrox diving) have been specifically designed to allow the various factors involved to be taken into account in a simple manner. They can be used for dives at altitude and also for determining whether a particular dive / journey sequence involving an excursion to altitude is permissible.
Many dive computers / dive panning software applications also compensate for the effects of changing atmospheric pressure although it is important that the user understands the implications of this for their particular computer / software.
Ascent rate
Maintaining a safe rate of ascent is vitally important in preventing possible decompression illness and the risk of gas embolism. The BSAC 88 decompression Tables (Air and nitrox diving) have been calculated based on a maximum ascent rate of 15 metres per minute up to 6 metres depth and 6 metres per minute from 6 metres to the surface and this must be adhered to when using the tables. The majority of dive computers and decompression/ dive planning software incorporate ascent rates of either 9 or 10 metres per minute throughout the ascent with the ability to configure the final depth at either 6m, 4.5m or 3m. On completion of decompression / safety stops all divers are recommended to follow the practice of ascending at 6 metres per minute to the surface.
Repeated multiple ascents should be avoided as they may result in decompression illness. Particular care should be taken when carrying out the various ascent training drills, for which specific advice is available.
'Sawtooth' dive profiles which involve repeatedly ascending and redescending over an uneven bottom should be avoided, but the practice of returning to the surface from maximum depth in progressively shallower stages is encouraged.
Assisted ascents
The National Diving Committee strongly recommends the use of an alternative air source (See Alternative source) as the prime method of assisted assent, and that all divers should carry such equipment.
Authorised branch dives
An authorised dive by a BSAC Branch is one carried out with the approval of the Branch Diving Officer.
A properly qualified and appointed Dive Manager shall be present and shall be in charge of all diving activities for the duration of the dive / expedition.
All Branch dives should be carried out in accordance with current BSAC recommendations for safe diving.
See the BSAC website http://www.bsac.org/page/674/branch-dives.htm for a full definition of dive authorisation and the responsibilities of those involved.
Page last modified: 1st Jun 2007 - 11:56:40