Commercial Diving;And How Deep is Deep?
by E. R. CROSS
A reader in New York asked, I am a certified advanced open water scuba diver. Will this help me become a commercial offshore diver? Probably not. An entry level commercial diver needs a great deal of additional training. This primarily includes the use of several kinds of diving gear, many kinds of tools and numerous skills to accomplish specific tasks. Divers are used for inspection and repair services in offshore oil. In addition, diving services are required both inshore and offshore in the installation of power plant intake and outfall pipes, in pipe pulls and in harbor construction. Whether the problem is cathodic protection of a platform, salvage of a vessel or underwater welding, divers need extensive training and experience in keeping underwater facilities on stream.
A commercial diver is defined as one who works underwater for pay. Within that definition there are several categories. Each class is divided according to the purpose of the dive rather than for the type of equipment used. Also, not everyone who works in the diving industry is a commercial diver. Employees who work in a dive shop or who crew boats are not necessarily divers.
All categories of divers need a lot more going for them today than they did a decade or two ago. It has been suggested the principal reason for this is that the science and technology of diving have changed so much that techniques have become more complex and involved. Possibly this is part of the reason. I suspect the real reason may be more complex than that.
Technifacts has been part of Skin Diver Magazine for more than 30 years. A review of questions received, and some solutions to the problems, indicate that not all recreational diving subjects are developed and taught on a need-to-know basis. It seems to me a number of subjects are taught in considerable detail but are not applicable to developing a safe diving profile. Other subjects are completely neglected or barely mentioned yet are important, some even critical, to diving safety.
Diving physics and physiology are fixed elements. They have not changed for the hundreds of years we have been part of the underwater environment. In spite of this, radical and extensive changes have developed in teaching these subjects. Technifacts has prepared a list of subjects in which suggested changes might improve dive training and dive safety. If you would like to receive a copy of the list, send a self-addressed, stamped envelope to E. R. Cross, Technifacts, c/o Skin Diver Magazine, 6420 Wilshire Boulevard, Los Angeles, CA 90046-5515. In the interest of improving dive training and safety, you are invited to indicate the areas you think need to be stressed more. Also, list the subjects you think are given too much significance. In addition, list the skills and subjects now taught that need to be modified to meet current technology or techniques. Comments on your training compared to your later experience as a diver are important. Technifacts would appreciate hearing from you.
HOW DEEP IS DEEP?
To help us recognize and accept our diving limitations, Technifacts periodically poses the question: How deep is deep? The deepest place in all the oceans is the Mindanao Deep in the western Pacific. It is about 10,850 meters (35,588 feet) deep. Pressure at that depth is nearly 16,000 psi. A crew of two in the bathyscaphe Trieste made the only dive to the bottom. They found forms of life living quite well on the bottom in nearly 6,000 fathoms. With our recreational diving limit of 130 feet we are hardly on our way to the deepest ocean bottom. Between the two extremes of how deep we can dive and the maximum depth, there are some interesting answers to the question of how deep is deep. Deep breathhold or scuba dives by individuals for the sake of records produce little if any scientific information that benefits diving.
Offshore, inland and coastal commercial divers now work in conventional surface air supplied helmet gear to depths of 180 to 200 feet. Scuba diving is permitted by OSHA regulations to those depths under limited conditions. From 200 to 300 feet, diving rigs using helium and oxygen as a breathing medium are used. To 300 feet, diving is usually performed on a similar mixed gas system, except descents and ascents are done in a bell. The diver(s) exit the bell only long enough to perform what is (usually) a short work time. This type of diving is sometimes referred to as bell-bounce diving.
Full saturation diving has been conducted to depths of nearly 2,000 feet. One classic saturation dive for a crew of eight divers was to 600 feet for 30 days. Several additional days were required for decompression. There is some indication that humans diving to depths greater than 2,000 feet may be subjected to tissue damage, besides the real potential for bends and other physiological problems.
Limited depths for divers is only the beginning in offshore work. From about 300 feet down the offshore industry is now using sophisticated ROVs or AOVs. In depths where divers can work, ROV and AOV systems sometimes support them. In water deeper than can be tolerated by divers, the ROVs perform the work.
Ocean News and Technology, (P. O. Box 2174, Palm City, FL 3499-7174 USA), reported in its November-December issue on some offshore production depths. Petrobras has set a new record, having begun production at the South Marlim 3B well in 5,607 feet of water. This tops Shells Mensa (at 5,499 feet) in the Gulf of Mexico. Then Ocean News asks, Whats next? Petrobras has Roncador at 6,022 feet. Shell has the ultra-deep Baba waiting at 7,626 feet. Exploration in 10,000 feet of water has already began.
Off Gabon (in West-Africas Gulf of Guinea) a tract for ultra deep oil development has been leased. Depth to the ocean bottom is just more than 16,000 feet. ROVs can be designed to handle any reasonable task at this depth.
The various classes of divers have already reached their physical and physiological safe diving limits. For the recreational diver on air, that limit is 130 feet. For the helmet air supplied commercial diver, it is probably 200 feet. For the mixed gas helmet diver, it is probably 300 feet with a bell-bounce diver going to 600 feet for short durations. For the mixed gas saturation diver, perhaps 2,000 feet. I suspect this should be the limit of pressure to which a human should be subjected. Beyond those lies potential pressure and possibly pressure related tissue volume problems.
There is probably no bottom at the deep end as long as the industry has the incentive to work deeper. The technology, in the way of ROV and AOV systems, is available. Specially trained divers, already familiar with ocean conditions, are available for operating the special systems. The total wealth of the oceans resources is unknown at present. As wealth becomes known, regardless of how deep, someone will find a way to get to and harvest it.