Diving: The Effect of Experience on Risk
Can safety be determined by a combination of time underwater and training? Read on as Peter Buzzacott, PhD reveals all.
INEXPERIENCE is often listed as a factor during analyses of deaths on roads, falls in climbing and fatalities in diving. But what is experience, and how does it affect divers’ risk of injury?
Experience involves some exposure to diving, but more than that it implies learning from that exposure, developing judgment about what to do when faced with similar situations in the future. The implication is that with time divers should be better equipped to make wiser choices. A single measure of experience for recreational divers does not exist, but some approximate measures may include the lifetime number of dives, years diving, highest certification level, number of dives made in the past year, number of hours diving and other logged diving variables. No individual measure has been identified as clearly providing the most protection against diving injuries. Each measure may be relevant to some hazards and less so to others.
A study of more than 1,000 recreational scuba dives in Western Australia found that 38 of the dives exceeded commonly accepted no-decompression limits and also that those divers were unlikely to have dived as deeply previously.[1].Though they had been diving for twice as long as the other divers (10 years vs. five years), they were reaching new depths and then incurring decompression obligations. This increased their risk of decompression sickness (DCS), though none reported symptoms of DCS following these dives. A 2004 survey of 305 trained recreational divers found that within two years of certification 20 percent had not dived for at least a year,[2]. but that does not mean they had given up diving. Research shows that divers often return to the water after a year or more of inactivity; for example, a survey of 528 recreational divers aboard dive charter boats in Texas headed for an offshore dive found that 13 percent had not dived during the previous year.[3].
In these examples we see both longtime divers going beyond their previous experience and relatively new divers returning to diving after more than a year out of the water. Both groups might be considered at risk when compared with divers who have recently dived to similar depths. This assumption forms the basis for requiring minimum levels of experience for participation in certain training such as dive leader, instructor, cave diver and closed-circuit rebreather courses. During these courses divers learn new skills, and this highlights the difference between experience and skill set: Experience is earned over time through exposure to diving, while skills may be learned. Experience enhances a diver’s level of comfort and self-awareness in the water, while skills concern a diver’s mechanical ability to perform certain tasks. Indeed, it is even possible for an inexperienced diver to be highly skilled, especially if the diver is eager to reach the “top” of the sport as soon as possible.
An analysis of insurance claims for DCS among DAN America members found that claims peaked for divers between the ages of 30–39, and thereafter claim rates fell in every 10-year period that followed.4 This may suggest that divers make safer choices with increasing age. We asked two experts in diving and diver training for their opinions on the interplay between dive experience and the risk of suffering a dive injury.
How do we measure experience?
Keith Cardwell: Experience in the context of recreational diving could be measured by number of dives, hours accumulated underwater, frequency and currency of diving experiences, locations dived and/or types of diving. Measurement of experience by many dive operations takes into account all of these indicators and often relies on reviewing log books and/or the presentation of a certification card both to confirm experience and to indicate level of certification (and assumed skill level).
Bill Oigarden: Experience is multifaceted. For scuba diving we usually think of experience as the classes we’ve taken, certifications we’ve earned and our time in the water. But I contend that experience also includes your lifestyle and how you view the world. A diver with an aggressive personality style might say he or she is experienced after a short period, while a more laid-back or reflective personality may tend to seek more knowledge because there’s always something new to learn. what I do. Buddy checks, ascent and descent checks, and regular communication with buddies are still necessary even after thousands of dives. Ignoring basic rules such as these is a precursor to trouble.
[1]Buzzacott P, Pikora T, Heyworth J, Rosenberg M. Exceeding the limits-estimated tissue pressures among Western Australian recreational divers. Diving Hyperb Med. 2010; 40(4):201–205.
[2] Buzzacott P, Pikora T, Rosenberg M. Post-training dive inactivity in Western Australia. Diving Hyperb Med. 2008; 38(4):197–199.
[3] Ditton RB, Osburn HR, Baker TL, Thailing CE. Demographics, attitudes, and
reef management preferences of sport divers in offshore Texas waters. J. Mar. Sci. 2002; 59:S186–S191.
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MEET THE EXPERTS
Keith Cardwell, PhD, has trained more than 2,000 instructors and established highly regarded training centres in Australia, New Zealand, the Maldives and the USA. Cardwell holds a master’s degree in education, postgraduate diplomas in business administration and sport and recreation, and a doctorate in the study of workplace competence for recreational dive instructors. He has been operating on the Great Barrier Reef out of Cairns, Australia, for the past 16 years.
Bill Oigarden, PhD, began diving in 1967 and was certified in 1974. His expertise now spans four decades of cave diving, technical mixed-gas deep diving and operating a charter boat in South Florida and the Bahamas. Oigarden, who has degrees in underwater technology, business management and counselling, is trained in all facets of open-circuit sport and commercial diving, recompression chamber operation and as a life support technician. He earned a doctorate in 2013 while researching personality traits among cave divers.
For the rest of this article (Scuba Diver Issue 7/2015, AA No. 84) and other stories, check out our past issues here or download digital copy here.