Diver Location Aids: HSE Report


An obvious criterion that can be used to compare the performance of devices against each other is the maximum distance at which a particular device can be relocated. Prevailing environmental conditions may well be expected to have considerable effects on the relocation distances of devices that are deployed at or close to sea level and require a visual sighting. These conditions would primarily include sea state and light intensity.

The components of sea state include wind speed, location, wave height and swell height. Sea state is grossly affected by geographic location. In enclosed waters, or near land with an offshore wind, wave heights will be smaller, and the waves steeper. Additionally, for any given wind force there may be considerable influence upon wave height in tidal areas. As sea state deteriorates it would be expected that the location distances of many devices would decrease.

The components of light intensity include 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. Light intensities fluctuate less markedly during normal daylight hours, irrespective of cloud cover and cloud type. The acuity of the human eye decreases with falling light intensities and the location distances of devices at sea level that do not provide an artificial light source will decrease correspondingly.

The aspect of a device above sea level and its colour may reasonably be expected to have some bearing on the relocation potential. Similarly, the elevation of the observers' platform above sea level will have an effect on relocation. The precise effects of this will however require determination as the size and type of boat will determine the observers eye height above sea level. Commonly used diving support vessels include inflatable boats and hard boats. Consequently, vessels of this type were used as the main observation platforms.


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