1. Introduction

The OUUEG safe diving practices document evaluates the risks inherent in SCUBA diving. All members of OUUEG are given a copy of the BSAC Safe Diving Practices booklet (Ref: 1.2.3), which details safe diving practices and complements this document.

1.1 Definitions

The following definitions are used in this document. Other useful definitions are found in the references.

1.1.1 Buddy

1.1.3 Instructor Grades

Definitions of Instructor Grades are found in the Branch Officers Handbook

1.1.4 Trainee

A diver, at any qualification level who is being taught or assessed by an Instructor. This training may take place in a classroom, pool, sheltered water or open water

1.2 References

The following documents have been used as references for the OUUEG Safe Diving Practices (SDP). Only the pertinent information has been copied from these references and they should be read, as though included in this document.

1.2.1 Oxford University Sports Handbook, Sports Ferderation, University of Oxford
1.2.2 Branch Officers' Handbook, British Sub-Aqua Club (Link)
1.2.3 Safe Diving Practices, British Sub-Aqua Club (Link)
1.2.4 Code of Practice, Oxford University Underwater Exploration Group (Link)
1.2.5 Risk Assessment, Oxford University Underwater Exploration Group (Link)
1.2.6 Pool Safety Officers Guidelines, British Sub-Aqua Club (Link)

2. Underwater risks

The underwater world is as inimical to human beings, and divers, as is the surface of the moon, and all divers need to understand and thereby minimise the risks involved in diving beneath the surface of the sea.

2.1 Running out of air

Running out of air is potentially fatal. Great care should be taken to avoid this situation. Divers should regularly check their own and their buddy’s submersible contents gage (SPG). In the event of an out of air (OOA) situation, special procedures must be in place to reduce the risk involved

2.1.1 Octopus Regulator

All divers should carry a second, redundant regulator, commonly called an octopus. This should be offered to the OOA diver as soon as possible. Great care should be taken that this regulator is working, and that each buddy team member is aware of its location and operation.  

2.2.2 Reserve Air

Both divers should plan to have enough air reserves to safely get two stressed divers to the surface, observing any required decompression stops, from any point within the dive.  

2.2.3 Long Hose Octopus

The octopus should be on a hose of at least 90cm length to facilitate the sharing of air.  

2.2.4 High Visibility Octopus

Divers should take care with equipment configuration to ensure that the octopus regulator is highly visible and easily deployed.

2.2 Regulator free-flows

2.2.1 Cold Water Regulators

Use of a cold water protected regulators can reduce the risk of free-flow due to freezing. The regulator should not be “breathed from” on the surface, as this can cause condensation to build up in the mouthpiece, which can then freeze. Wait until the regulator and the mouth are underwater before starting to breathe from the regulator.

2.2.2 Free Flowing Regulator

2.2.3 Octopus Ascent

2.3 Entanglement

Nets, ropes and discarded fishing lines are common on many dive sites. All divers should take care to avoid being entangled in this debris. The lines from a surface marker buoy being used to inform the surface cover of a divers whereabouts, plus buddy lines and penetration lines, can also be a source of entanglement. Divers should take care to deploy and recover line in a safe manner.

2.4 Separation from surface cover

2.4.1 Surface Marker Buoys (SMB)

All divers should use a surface marker buoy (SMB) wherever possible. If an SMB would cause problems during the dive (i.e. penetration diving) a delayed SMB must be taken and used on ascent. This enables the boat or surface party to follow the progress of the divers. It also provides surface flotation at the end of a dive should it be required.

In the event of separation from the surface party or boat, the dive marshal/coxswain should initiate emergency procedures. The diving pair will not know about separation until on the surface. When arriving on the surface and discovering that separation has occurred, the divers should:  
1. Inflate their BC’s.
2. Remain close together.
3. Consider swimming ashore if possible.
4. Deploy any surface detection aids – e.g. Strobes, flags, flares, torches etc. – as appropriate

2.5 Separation from buddy

2.5.1 Separation below surface

In the event of buddy separation, a diver should conduct a brief search for his/her buddy. This should take no longer than one minute and consist of 2x360 deg. searches remembering to look both above and below.

2.5.2 Action on Separation

All divers in the group should then ascend directly to the surface, observing any decompression stops required. The alarm should then be raised with the surface cover or boat coxswain.

2.5.3 Missing Diver

If any divers from the separated team have failed to surface within five minutes of the first diver surfacing, emergency procedures should be initiated

2.6 Marine life

There is very little danger from marine life around the British coastline. However, care should always be observed with any wild animals

2.6.1 Sealife Dangers

Crabs and lobster can give a nasty pinch and break, or worst case, trap fingers. Seals will bite if provoked, as will dogfish and conger eels. Jellyfish can sting exposed skin, and care should be taken to avoid touching their tentacles.

2.6.2 First Aid

If a diver should be injured,or stung, by an encounter with a marine animal, then appropriate first aid and medical attention should be sought as soon as possible.

3. Advanced diving risks

3.1 Deep dives

Dives deeper than 30 meters require a higher level of planning and equipment redundancy.

3.1.1 Redundancy

The use of “Pony Bottles” as a minimum level of redundancy should be considered. Divers should pay particular attention to their equipment, and ensure that it is in good order. Generally speaking, the deeper and longer the dive, the greater should be the level of redundancy utilised.

3.1.2 Additional Equipment

All divers must carry:
   1. A dive timer and depth gauge, or a dive computer.
   2. A slate for communication and recording the dive plan.
   3. A knife or line cutter.
   4. A torch.
   5. A redundant air source. 
Each pair must also have an SMB (delayed or standard) and reel between them, and be familiar with its use.

3.2 Decompression diving

For dives involving greater than five minutes total Decompression time, then full breathing gas redundancy must be included in the Dive Plan

3.2.1 Redundancy Planning & Equipment

3.2.1 This may be in the form of a Pony bottle, but ideally would be in the form of twin cylinders. These may be either be independent or manifolded tanks. The dive plan must formally examine the possibility of either diver losing all access to air, and having to decompress and surface using their buddies gas supply. The divers equipment configuration must enable this to occur safely and to the satisfaction of all divers involved.

3.2.2 Decompression Stations

Where possible, decompression should be performed on a static shot line. In heavy current, the use of a delayed SMB should be considered. The boat coxswain must be notified of the decompression procedure. It is good practice that all dive pairs/teams should observe the same procedures. I.e. all should decompress on the shot line, or all should drift with delayed SMB’s. Any combination of different Decompression procedures could prevent the boat handler from giving adequate cover to all divers. In cases of high current and long decompression, the use of deco-stations should be considered.

3.3.3 Additional Deco Gas

Where practical, spare gas should be placed on the decompression line, station or shot line. This will allow divers to safely complete decompression in the event of running low on air.

3.3 Overhead environments

3.3.1 Guidelines

All dives into the overhead environment should utilise a continuous guideline back to clear open water. In the case of “swimthroughs” where a different exit point will be used to that of entry, guideline should still be used unless regular, constantly visible, points for egress exist

3.3.2 Rule of Thirds

Penetration dives must utilise the “rule of thirds” for gas management. One third of the available air should be used for descent and bottom time, one third for ascent and decompression, with the remaining third being kept available as a reserve or bail-out in case the diver, or his buddy, has an equipment failure, or OOA, at the deepest planned point of penetration. Overhead environments should not be entered with less than 150 bar remaining in the diving cylinder.

3.3.3 "Long Hose" Octopus

The use of an at least 200 cm "long" hose on the donated regulator is highly recommended for this type of diving, particularly should the dive require an “in-line” egress while sharing air.

3.3.4 Torches

All divers should carry a minimum of two torches.

3.3.5 Redundant OOA Cylinders

3.4 Oxygen enriched mixtures

Nitrox is now quite commonly used as a breathing gas of choice. Nitrox is simply normal air which contains a higher percentage of oxygen than air, and therefore a lower percentage of nitrogen.

3.4.1 Extended bottom times

Within rigid depth limits, Nitrox can offer either an extended no-decompression botton time, or a shorter decompression time

3.4.2 Lowered risk of DCI

A well planned and executed Nitrox divecan give increased safety from both sub clinical and actual decompression sickness risks.

3.5 Oxygen toxicity

The increased percentage of oxygen in any given breathing mixture means that oxygen toxicity is a more serious concern than with air diving. Oxygen toxicity is not a concern when diving with air until a depth of 57m, whereas with a 36% Nitrox, the equivalent oxygen toxicity ppO2 would occur at 28m. Although Oxygen toxicity underwater is a potentially fatal condition, this risk can be virtually eliminated by using certain procedures.

3.5.1 ppO2 1.4 limits

For the "working" section of the dive, the ppO2 must not exceed 1.4 bar. Careful monitoring of depth must therefore be performed.

A maximum ppO2 of 1.6 is acceptable during a decompression stop if using separate decompression mixtures.

3.5.3 Nitrox training

All divers wishing to dive Nitrox must have completed recognised training in its use before undertaking dives using these gases.

3.5.4 Oxygen Toxicity

Due regard to issues of accumulated oxygen toxicity (both CNS and pulmonary) must be observed

4 Surface risks

Diving can be inherently risky, and divers can put themselves at risk to several non surface related injuries every time they go beneath the surface of the water.

4.1 Decompression trauma

Decompression illness (DCI) is caused by bubbles of nitrogen forming in tissues of the body, causing the obstruction of blood flow, and other consequential problems. Every dive carries a risk of DCI. Certain procedures should be observed to reduce this risk

4.1.1 Decompression tables

Dive within recognised air or Nitrox decompression tables, or the information presented by an air or Nitrox dive computer.

4.1.2 Ascent rate

Do not exceed an ascent rate of 10m/min at any point of the ascent, and take at least one minute to travel from 6m to the surface.

Conduct a 3 min safety stop on every dive

4.1.4 Dive limitations

Do not dive when dehydrated, excessively tired or unwell

4.1.5 Dive protection

Stay warm on the dive

4.1.6 Diving breaks

On a series of dives, take a 24 hr surface interval after three days of diving.

Use Nitrox if properly trained and where available.

4.1.8 DCI incidents

In the unlikely event of a diver suffering from DCI, a suitably qualified person should administer pure oxygen immediately. Medical assistance should then be sought, preferably from a hyperbaric physician. Local coastguards are able to connect VHF radios to appropriate medical personnel. Recompression treatment should be sought at the earliest possible opportunity.

4.2 Pulmonary barotrauma

 This is caused by air trapped in the lungs expanding on ascent and tearing the lung lining. Slow ascent rates and breathing normally at all times should prevent this from happening. In the event that it does occur, the treatment is the same as for DCI. Administer pure oxygen and obtain medical assistance as soon as possible.

4.3 Non-pulmonary barotrauma

Barotrauma to the ears is also possible. This is damage to the eardrum caused by descent or ascent without clearing the ears. A burst eardrum is excruciatingly painful, and will cause dizziness and vertigo. This would be a dangerous underwater condition. The risk can be minimised by clearing the ears frequently and not using force to do so, as this can exacerbate the problem. Diving with a cold reduces the ability of the ears to “clear” and must not be undertaken.

4.3 General surface based injuries

 Injuries can be caused to surfacing divers by boats, particularly in popular tourist areas where there is much boat traffic. All divers should surface directly underneath their SMB. They should also look around, and listen for engine noises just before surfacing. They should be prepared to make a rapid descent out of danger if any nearby boat activity is suspecte

5 Dive boats

Diving from boats, whether Club boats, or commercial craft, for most divers is what diving is all about. Generally dive boats fall into two separate categories, RHIBs, and Hard Boats.

OUUEG possesses two seaworthy rigid hull inflatable boats (RHIB’s). These craft are inherently buoyant, and almost impossible to sink. They utilise outboard petrol engines for power

5.1.1 In order to protect against most eventualities, and to enable the boat coxswain to deal with most scenarios, the following items should form the minimum boat kit for every Club boat voyage

In order that the coxswain can deal with any scenario, the following items must be carried on every boat.  
    1. Working VHF radio.
    2. Compass
    3. Anchor and sufficient line.
    4. Sufficient petrol and oil for the return journey plus one half again.
   5. Working oxygen kit, with enough O2 capacity for two diver's needs for the journey back to shore and transfer         to an ambulance, helicopter or hyperbaric chamber.
    6. First aid kit.
    7. Tool kit.
    8. Flares.
    9. Oars.
   10. Divers down “A” flag.
   11. Drinking water.

5.1.2 Boat trip precautions

Before embarking on any journey, the boat coxswain should leave information with the Dive Marshall or the coastguard if the Dive Marshall is on the boat, regarding the departure time, number of people on board, destination and estimated time of return. On longer journeys, the coxswain and the Dive Marshall should consider using two boats and travelling as a pair so that assistance may be given if required.

Economy of scale, ease of use, and less responsibility are a few of the reasons why more and more diving expeditions are undertaken by hiring a commercial hard boat

5.2.1 Benefits of chartering a commercial dive boat

    1. Local knowledge
    2. Ability to go further off shore
    3. A larger more stable diving platform

5.2.2 Boat kit for commercial dive boat diving

The risks of diving from a hard boat are the same as when diving from a RHIB. When chartering a boat, you should make sure that all of the relevant equipment identified above is carried.

The following risks exist when using boats at sea

5.3.1 Engine failure

An engine failure at sea can rapidly become a serious situation, if not dealt with correctly. To reduce the likelihood of this occurring, the following steps should be taken.
    1. Ensure boats and engines have been serviced within the recommended time period.
    2. Check that engines are running well, and that no problems have been reported.
    3. Carry enough fuel for the journey.
If any of the above criteria are not met the journey must not be undertaken. Should an engine failure occur, common sense will dictate the appropriate procedure. However, the following will need to be assessed:
    4. Can the problem be fixed?
    5. Are there divers in the water, and are they becoming separated from the boat?
    6. Is the boat in any danger by drifting? If so, anchor the boat.
    7. Is there any nearby assistance.
Before the situation develops, i.e. divers become lost, or the boat drifts into a dangerous position, assistance must be sought. This should be done as soon as possible. Assistance can come from nearby boats or the coastguard. Obtaining assistance is likely to involve the use of the VHF radio.

5.3.2 Becoming lost

5.3.3 Overdue divers

In the event of divers not surfacing after the pre-arranged time, they should be recalled. This can either be by tugging on the SMB line, by deploying a weighted “thunderflash”, or some other appropriate means. Divers failing to return after the recall signal (accounting for any expected decompression obligations) should be considered lost.

5.3.4 Lost divers