A diverse range of location aids is available for use by divers in order to promote their relocation and recovery from the water. Location devices may be used routinely in the course of normal diving operations to facilitate a particular diving procedure or they may be used to attract attention when the diver has become separated from their diving support facilities.
Recreational and commercial divers undertake many thousands of dives each year with most of these dives taking place without incident. The majority of incidents that do occur take place on the surface and each year there are numerous reported incidents of missing or lost divers. The causes of these are numerous but may include; poor navigation, offshore winds or tidal currents, location devices not used or used ineffectively or incorrectly, engine failure, failure of skipper or boat crew to monitor divers position, deteriorating weather resulting in increased swell, waves, failing light etc.
Many recreational divers use a wide selection of location aids for dives under particular conditions. The most common devices in use are surface marker buoys (SMB's). These marker buoys are colloquially referred to by divers as 'deco bags', and they are generally conspicuous in shape, size, and colour to provide visible markers of the location of a diver. They may be inflatable bags that are inflated prior to the descent, thus marking the divers position from the onset of the dive, or more typically, these devices are carried by the diver during the course of a dive, deflated and stowed in a convenient position. The device may then be inflated underwater during the ascent. The inflated buoy ascends to the surface thus marking the divers position underwater. This latter form of SMB is generally referred to as a delayed SMB. These location devices are frequently used by divers undertaking decompression stops. The marker buoy enables a diving support vessel to observe the divers position and the positive buoyancy of these buoys facilitates the diver to carry out stops at more precisely controlled depths over longer periods of time.
Commercial diving contractors undertaking inspections, maintenance and fabrication work, most frequently perform these projects while adhering to strictly controlled procedures and would rarely require any need for location devices. Other groups of divers at work may include scientific, archaeological, media and recreational instructors. A number of working divers regularly dive for shellfish. Commercial shellfish divers periodically work in strong tidal areas utilising 'solo' diving techniques. Frequently there may be two or more divers in the water at any one time. A coloured buoy or combination of buoys is used to mark their position. On occasions, significant distances may separate the divers and during periods of reduced visibility, moderate sea states or diving in areas where there are numerous similar buoys marking fishing creels, the diver's buoy can be confused or 'misplaced'. Diving contractors are required to undertake diving operations whilst adhering to relevant legislation and Approved Codes of Practice. Risk assessments must be carried out for these diving projects to identify any site-specific hazards and their risks. Using this information, diving project plans must be prepared. Amongst many other components, these project plans should identify the techniques to be adopted and the means by which a diver would be relocated and retrieved from the water in the event of any foreseeable emergency. The ability to monitor the divers position whilst underwater is of paramount concern for the duration of the dive. Consequently, particular location devices may be beneficial in both instances.
A wide range of other surface marker aids are available for use by divers. These include pyrotechnics, telescopic flags, fluorescent dye, flashing strobes, whistle's, torches and personal EPIRBS (Electronic Position Indicating Radio Beacons). Divers have used a selection of these devices to good effect for many years. Some devices have been trialed by manufactures under a range of environmental conditions and consequently particular claims may be made. Some groups of divers have also conducted their own independent assessments on location devices. Much of this work has only provided qualitative information regarding how effective a particular location device is considered to be. Little work has been undertaken to provide more quantitative evaluations on their performance or limitations against one another under comparable conditions. The requirement of any location device is to promote the recovery of an in-water diver. Any location aid that can consistently and reliably provide this, would be an asset in those instances when divers find themselves for whatever reasons, separated from their diving platform.
This study assesses a diverse range of diver location devices under an extensive range of environmental conditions to provide an assessment of their particular benefits or limitations. The main objectives were:
To ascertain and define the performance limitations of diver location devices from the most commonly used diving platforms, namely inflatable boats and hard boats.
To provide recommendations on the optimum type or combinations of diver location devices for particular environmental conditions and search facilities.
