Rig and platform operations at Kishorn in the 1970's utilised a different type of diver - the professional.Commercial diving as a small and specialised industry has always been a seedbed for the growth of strong, if somewhat eccentric, personalities. Diving is difficult, demanding, uncomfortable and potentially dangerous. It requires physical courage, strength, perseverance and endurance seldom required in other areas of work: each time he jumps in the water, the diver knows that his life is directly dependent on his equipment and the efficiency of his surface support team. He knows that the water is likely to be brutally cold and the current running so swiftly that most of his strength will be used just getting to the job and hanging on. The job he will be expected to do could be something very simple like inserting a steel O-ring between two wildly oscillating flange faces and then bolting up the flanges. After he hits the water he may as well be blind because the majority of inshore commercial diving work is done in zero visibility. He may well be working in a tar-black mud ditch with crumbling sides where his only reliable perceptions are those received through his fingertips. He may also know from bitter experience of the appetite of pipe flanges for divers fingers.

Here we can draw a difference between sport and commercial divers: the former, when conditions are unpleasant, can come out of the water, have a cup of tea, pack up for the weekend and go home ready for his job on Monday morning; the office of the commercial diver is the tar-black ditch, the polluted, rat-infested river, the diptheria or polio-infected outfall of a sewage pipe. The latter may not enjoy his cup of tea until he has spent 5 or 6 hours in the water.

After his job has been completed, or he has run out of bottom time, he will possibly have to endure hours of teeth-chattering misery while hanging off in the cold water for his decompression stops. Physically sapped after his last stop, he may have a 15-foot climb up a rickety ladder with missing rungs, dragging heavy equipment up the side of a heaving, wave-swept barge.

On deck, tenders will strip him of his gear and rush him into a deck chamber where he can comfortably relax for a few more hours of decompression in the dank, 120-degree heat of that confined steel prison. When the chamber door opens at the end of the decompression, the diver knows (if he doesn't come down with the bends) that he will have at least twelve hours off before he is required to do it all again.

This type of diving is in strict contrast to saturation diving, when a dive team may live and work from a deck-mounted chamber for approximately 30 days at a time.