Diving and Undersea Vehicles

Subsea tasks may have to be accomplished at great depths, of perhaps several hundred metres, so the use of divers using conventional breathing apparatus may not be possible. For example, the inspection of the RMS Titanic at a depth of approximately two and a half miles, where pressure is in the region of 7000 psi, was a superb illustration of the effectiveness of the combined use of remotely operated vehicles (ROV) and manned submersibles. The self-propelled submersible vehicle 'Alvin', with no connection to the surface, carried three men in its chamber at atmospheric pressure. 'Alvin' descended near to the seabed and then released a small ROV 'Jason', which remained linked to 'Alvin' by means of its umbilical.

The ROV offers a means of intervention, theoretically to all depths, without any of the limitations associated with conventional diving. At present, the majority of ROVs are tethered to surface or subsea installations or craft. The 'tether' carries control signals and power for television, lights, etc. Clearly an important feature of the ROV is the television link which enables the operator to navigate the craft and perform tasks with manipulators.

The main feature of a manned submersible, or its smaller, more modern version – the atmospheric diving suit (ADS) – is some form of chamber containing air at atmospheric pressure, inside which the pilot can go underwater without the physiological limitations associated with conventional diving. However, despite the physiological advantages of atmospheric diving, the pilot's ability to carry out tasks is severely limited by the need to use cumbersome manipulators.

Subsea tasks have normally been accomplished by conventional divers wearing some form of breathing apparatus; they are subject to the effects of the ambient pressure at their working depth. Working depths for North Sea divers vary from just a few metres down to 200 metres where the divers are working in 'saturation', often living for days in pressure chambers at the ambient pressure involved. Occasionally work has to be done at 300 metres, which is still within the limits of modern diving systems, and there is interest in increasing this depth capability to 450 metres. The maximum working depth for conventional divers is limited by the effects of breathing at depth, and the effects on the body caused by excessive pressures. However, ADS and ROV intervention are theoretically possible at any depth, the only limitations being mechanical and environmental.

Despite these advances, there will always be a role for the conventional diver, particularly since most work takes place at relatively shallow depths. However, it is very important nowadays for the diver to combine his diving abilities with other technical skills, for example fitting, welding, engineering and inspection skills.

Diving skills are also needed in several other careers: the armed services, the police, science (particularly marine biology and archaeology), the media and in the training of recreational divers.

HOW THEN CAN I FOLLOW A CAREER AS A CONVENTIONAL DIVER?
One thing is clear: Unless you hold a government certificate of diver training you are not legally permitted to dive professionally in UK waters. Your later career will be helped considerably if you have qualified in a skill or trade before taking an approved course and entering the diving industry. Leisure diving experience is useful, as it means that you know whether or not you like being underwater, but it is not mandatory, as the requirement of a career diver is that he or she should be capable of working underwater. The reputable schools run aptitude tests to help would-be divers determine whether or not they are suited to a career working underwater. Diving can provide an interesting and worthwhile career in itself, but if you hold a trade or skill it is always possible to revert to this later in your working life. Other key roles such as dive supervisor and dive superintendent are usually reserved for people who have had diving experience.

For those with an interest in diving but who do not want to work underwater, other career options are possible, such as ROV pilot or inspector, inspection controller and life support technician.

Although training courses for ROV pilots do exist, most training is normally provided by the manufacturers or operating companies. Information on courses is available from International Marine Contractors Association (address below).

Another approach is to go into diving with a qualification such as a degree or diploma in some branch of engineering. Choose a course that will enable you to specialise in some degree of underwater or offshore engineering, via options or a project. At the same time, learn to dive or continue your diving, perhaps through the university or college sub-aqua club. Following such education, you can train and then work as a commercial diver until such time that your engineering qualifications and your practical underwater working experience enable you to move into underwater engineering design and management. With the industry becoming more technical, people with such a background are becoming increasingly valuable.

For those wishing to combine diving with their interests in science, then it is necessary to qualify fully in the area of science, and additionally train as a diver. Some courses in marine biology, underwater science and marine archaeology include diving training, but it is necessary to identify such courses by detailed examination of the course syllabi.

March 2002

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