Surfacing from a dive to find you've been abandoned by your dive boat is a diver's worst nightmare. This article will help to prevent this from happening and if you do find yourself in this positition, how best to survive.
Open Water filmmakers Chris Kentis and Laura Lau say the inspiration for their movie, shot during the couple's weekends and vacations, was the real-life story of Thomas and Eileen Lonergan. In 1998, the young Americans, who were never found, were stranded when their 26-passenger vessel departed without them from a popular dive site along Australia's Great Barrier Reef.
In another case, in 2000, a Californian couple were inadvertently left behind by a commercial dive boat several miles off Key Largo in Florida, and spent the night clinging to a steel light tower before being rescued. More recently, Dan Carlock, a 45-year-old Los Angeles diver who had trouble equalizing the air pressure in his ears, became separated from his group off the California coast and surfaced to find himself in fog, alone, several miles offshore. He was rescued several hours later by a sailboat manned with Boy Scouts.
The incidence of being left on site by the dive boat is extremely rare and there is probably more chance of winning the lottery, however it does happen and taking sensible precautions can ensure that you and your buddy return safely to your boat, every time.
The dangers of being left behind include:
- Dehydration and thirst
- Severe sunburn and immersion injury
- Marine animal injury
The ability of the observer to see a diver in the water (relocation distance) is dependant on the following:
- The distance between the observer and diver.
- The colours and brightness of the diver equipment i.e. hood and BCD.
- The brighness, colour and height of any 'attention getting devices' attached to the diver e.g., Flags, Strobes, SMBs etc.
- The elevation of the observer above sea level.
- The prevailing environmental conditions:
- Sea State - The wind speed, location, wave height and swell height.
- Light Intensity - This includes cloud cover, cloud type, precipitation and time of day. The period of time from darkness to daylight varies by day and the intensity of light increases and decreases quickly over a short period of time during the sunset and sunrise hours.
Skippers will position themselves so they would not be looking into the sun for divers.
Typically, the following relocation distances apply:
|Strobe on flag
As in all risk management there are a number of actions that divers can take that will firstly, minimise the probability of being left and secondly, maximise their chances of survival, should the unthinkable happen.
Equipment - Get brightly coloured suits, jackets, fins and hoods with reflective patches if possible. It is much harder to see a diver wearing black from a boat or the air.
BCDs - Make sure they will keep the diver positioned on the surface, in a head up position.
SMB - Always carry a delayed SMB. Aqua lung do a hands free, SOS back pack, see picture right.
Visibility Safety Aids - There is a range of additional equipment and tools that can ensure divers get noticed whilst out at sea. These include:
- Folding Flags - telescopic, bright and yellow
- Rockets, Flares and smoke - day and night flares are available and can be carried by the diver e.g., Pains-Wessex Mini flare 3 and the Pains-Wessex Day/Night Distress Signal. Whilst they may provide substantial relocation distances, pyrotechnics are not specifically designed for going under water. These devices are relatively expensive and their reliability after long term exposure in a marine environment is not known.
- Strobes - good battery life, good in the dark. Better attached to the top of a flag.
- Torches - good for attracting attention at night and dusk
- Glow sticks - helpful but not as good as torches
- Mirror - useful for reflecting light, no battery problems, some suggest using CDs
- Fluorescent Dyes - dyes can easily be seen from the air, not very good for sea level.
Audible Safety Aids
- Whistles - useful, but volume limited
- Screamers - battery and air driven, much louder
Survival kits - Survival kits may include all or some of the above.
Personal EPIRBS (Electronic Position Indicating Radio Beacons)
An EPIRB is a small self-contained battery operated radio transmitter which is both watertight and buoyant. The essential purpose of an EPIRB is to assist in determining the position of survivors in search and rescue operations. Certain classes of vessel have a mandatory requirement to carry EPIRB's which operate on a frequency of 406.025 MHz. Once activated, an EPIRB's should not be switched off until rescue is completed. However once the incident is over, it is important that the EPIRB is deactivated. There are two types of approved EPIRB's available in the United Kingdom which are suitable for small ship use:
- The small simple type which operates on the aeronautical frequencies of 121.5 and 243 MHz.
- The more sophisticated model which operates on the frequency of 406.025 MHz, with the addition of 121.5 MHz for aircraft homing. The 406 MHz EPIRB's additional facility is a unique identification code which is registered to the vessel on which it is carried. 406 MHz EPIRB's must be registered with with HM Coastguard.
Modern EPIRBS are small, tough, light and integrate EPIRB GPS with 406MHz so Search and Rescue (SAR) services pinpoint EPIRB location within minutes compared with nearly an hour with 406MHz alone.
PLBs (Personal Locator Beacons) are small radio devices that function similarly to the larger EPIRBs. They are not powerful enough to send a signal to a satellite and initiate a rescue scenario involving planes and boats, as will a proper EPIRB, but they rely on someone equipped with a suitable tracking device knowing that a diver is lost.
The Sea Marshall divers beacon costs about £170 including VAT. It is small enough to incorporate into a dive jacket, requires no exterior waterproof box and withstands depths of 300 meters. In the event of a surfacing scuba diver being lost, the PLB can be activated. It then transmits a signal which can be picked up by an onboard receiver to allow the crew to organize the recovery of the lost diver or if necessary to call upon the search and rescue (SAR) teams to take over the operation.
The SAR organisations can then track the PLB signal on their own equipment. The PLB signal is set to 121.5MHz, which is the fixed, agreed international homing frequency. All Search & Rescue vehicles are outfitted with the correct equipment to monitor and track this signal. This model has a built-in electro-luminescent light and wire antenna encased in a clear neoprene. This gives a visual reference to the search teams in addition to the transmitted signal.
The Dive Boats
The risks and precautions are slightly different, for divers that dive from a hard boat or a RIB, for example with a single engines Rib there are additional risks of engine failure and possibly an inexperienced crew.
Hard Boat Diving
- Diver Operator - Choose a dive operator and dive site wisely. Do your homework on the operator's qualifications and previous history.
- Check out the boat -Check out the boat and skipper before diving, Make sure they take safety seriously, check radio, emergency equipment and spare boats. Ask about:
- rescue action plans
- the history of the motor
- the credentials of the crew
- the system they use for counting divers in and out
- who they call for assistance.
- Be alert - to location of the nearest land
- Know your limits - Be honest about your own abilities and the local conditions, particularly with issues such as strong or unpredictable currents, weather or off shore diving.
- Inform the skipper - Let the skipper know if you are carrying an EPIRB
- Get Noticed - The risks will be higher if you are a single pair of 'quiet' divers, joining an unknown boat and unknown crew, so make sure you are noticed by the crew and other divers. Leave your personal clothing and possessions in such a way that it will be obvious that you have not returned from your dive.
- Get Dive Fit - Before each dive make sure you are:
- Nourished, rested and hydrated
- Adequately protected from the cold
- Adequately protected from sunburn
- Dive Brief - Listen very carefully for instructions.
- If it is a drift dive, stay with the group
- Respect any time limits
- Make sure you know the tide and wind conditions
- Make sure you know where the nearest land is
- Make sure that the dive site (both entry and exit points ) are visible from the boat. This is particularly relevant if you are being transported to the site via a RIB.
- Ask any questions, be clear about depth, currents and timings.
- Make a pact with another dive buddy team on board that you will visibly check and ensure each other is aboard before you let the boat move off site.
- Don't dive - If the sea is too choppy, unsettled or there is mist or fog and land is afar.
- RIB is operational - Ensure that the engine is properly maintained, there is sufficient fuel and that all of the electrics work, particularly the radio and GPS. Also make sure there is an adequate anchor in case of engine failure so that there is less chance of the boat drifting off site.
- Shotline - Make sure a shotline is used, with sufficient rope to ensure it is securely anchored at the bottom, this will act as a point of reference. Use a tidal buoy as well.
- Competent Cox'n - Ensure the cox'n is comfortable using the Radio and restarting the engine(s). Where possible leave a minimum of two competent crew on the RiB.
- Recall Signals - Make sure all divers understand the recall signals.
- Backup - Take mobile phones as a backup.
- Take Notes - Ensure the crew write down the time divers submerge and give them a time by which if they haven't surfaced the Coast Guard will be called.
- SMBs - Ensure all divers have their own SMB and are requested to deploy them if they move off site. Do not bubble watch.
- Rib Positioning - Position the Rib so that the crew have the best view of the dive site.
- Where possible, start your dive by swimming up current after orientating yourself.
- In good visibility stay with the group.
- Develop your navigational skills (see Underwater Navigation).
- If you drift off the allocated area e.g., a wreck site, inflate an SMB to advise the surface craft.
- Respect and plan for, any time limits imposed by the skipper or cox'n.
- Avoid long decompression stops in strong currents. Remember a 15 minutes deco stop in a 2 knot current will move you half a mile. In any event inflate an SMB as soon as possible to advise surface craft.
If you surface from your dive and the boats is steaming away from you or worse still, nowhere to be seen you have to manage the situation. Do the following.
- Inflate BCD - If air is short do it manually.
- Inflate the SMB - These are much easier to see.
- Protect from cold - Inflate suit (may also lift you out of the water more). Keep hood and gloves on, and mask if vision is unimpeded. Draw knees up and huddle together. Use snorkel if choppy. Note: you may be more visible without a hood.
- Attract attention - Use whatever tools you have to attract attention, e.g., torch, mirrors, whistles, shouting and waving. Lift your feet up, if your fins are the only brightly coloured equipment you have.
- Note details - Write time, approximate location and the speed and direction of current on your slate.
- Don't fight the current - This is much easier to say than do, especially if you see your boat in the distance.
- Drop weights - but keep the belt.
- Swimming - If you swim, swim diagonally with the current toward any known dry land. Don't swim just to warm up, this just wastes energy and conversely doesn't get you warmer (see Cold Water Diving).
- Drinking - Do not, on any account drink the sea water.
- Stay with the group - Use a method of securing divers together by using empty weight belts, buddy lines or other straps. This gives a larger target for searchers.
- Maintain morale - The 'will to live' may be crucial to your survival, never give up hope. Being lost at sea may be a terrifying experience but you are much easier to see than you may think. Good skippers will know the exact location of the dive site and also the direction of the current at a given time. Remember that there will be rescue attempts and searchers.
See the PADI Video for more information, the quality is not particularly good but the messages are helpful.