The safety of the diver when he is conducting Air Diving Operations is largely dependant on the accurate control of his depth and the time he has been under pressure. At present the depth information is gathered by use of a manually operated pneumo-fathometer and the time is taken by stop-watch. The whole operations is recorded by a hand written log. The Diving Supervisor is required to operate this primitive system which results In Inaccurate data and reduces the control and safety of the operation. UKOOA, AODC and HSE have co-operated to produce a minimum technical specification for the introduction of electronic depth/time sensors linked to computer based logging systems Their aim is to ensure that all offshore a r Diving systems are provided with such systems from 1994 onwards. This will Improve the safety of air Diving operations and enable satisfactory health, safety and operational analysis to be undertaken which will be based on reliable data gathered from the whole Diving Industry.
In air diving operations the accurate measurement of the diver's depth and the time he has spent under pressure are essential to his health and safety and to the correct selection of his decompression schedule.
At present the diver's depth is monitored by use of a pneumo-fathometer and pressure gauges. HIS time under pressure is monitored by stop watch and the whole operation is recorded by a hand written log kept by a very busy Diving Supervisor.
The pneumo-fathometer is an open ended a r hose down which the Supervisor can pass compressed ar. When he shuts the a r pressure off, and in all the water has been expelled, he can then read the resulting back pressure on the gauge. If the diver goes any deeper his gauge will not indicate his new depth unless the Supervisor remembers to re-pressurise the line.
The product of this system is less than satisfactory and means that the accuracy of the depth information presented to the Supervisor in questionable and that the reliability of tune and depth information recorded in the log are also questionable. The need for the Supervisor to be actively concerned in obtaining this information and writing a log can be detrimental to his concentration. In the event of an emergency he must concentrate on the priority task of assisting the divers and as a result the production of an accurate log is unlikely.
Given the level of technology available offshore this situation is surprising. For many years Remotely Operated Vehicles (ROV) have made routine use of electronic depth sensors and computer generated timing systems which are continuously displayed on video monitors and permanently recorded on either video tape or computer generated software. On the whole ROV's are owned and operated by diving companies but despite this the technology transfer has not occurred, presumably because of the cost implications.
