June 1, 2010
On Safety, Dogma, and Objectivity
Originally published in June 2010 issue of AAUS' E-Slate. Reprinted with permission of AAUS and the author, Jim Washburn, Diving Officer, Oregon State University
Having attended many symposia/conferences over the course of 35+ years (in fact pre-dating AAUS), there have been certain recurring themes that become apparent, as well as a tad perplexing. One theme in particular seems to commonly re-occur during discussions on safety, when using diving as a tool for research. To wit: The never-ending rationale for adding additional dive equipment, by applying the greatest sales pitch of all: SAFETY.
The supposition that one is safer with a pony bottle, and/or two knives, redundant timers, a second regulator, a light (or two), wet and dry suit pockets and attachments, etc., while also disregarding their cumulative effects, needs to be directly challenged by someone, and that someone should be AAUS. We should be in the business of not merely safety, but also facilitating research. We have allowed ourselves to be driven, to a large extent, by the marketing aspects of the diving industry, and thus, have become more than a tad dogmatic.
For the moment at least, let's play in the scientific ball park. Forty years ago, a conventional diver (even in academia) had about 160 total parts of dive equipment. These parts were literally the individual itemized components, e.g., mask (with a strap and buckles), snorkel (including a keeper), fins (including straps and buckles), regulator (with 74 parts), etc. I am sure you get the idea. By the 80s (my last count), the somewhat typical diver was then packing around 74% more parts than a 60s diver. Since the 80s it is reasonable to assume the collection of items, parts, and components has gone far beyond the 282 parts on an 80s diver. The result is an important and largely unaddressed issue for the diver: drag. It is worthy of comment that adding mass to a diver is not a freebee. Mass is, well… mass. Thus, it's subject to all the laws of physics, including inertia. Which leads us to a discussion of drag coefficients (or better yet, power and energy output).
Let us say you have a clone with your identical water skills. Assume you have a moderate additional amount of dive gear, relative to your clone, resulting in 10% less speed (an accurate experimental value), while moving through the water. You say to yourself: "Self: Do I care about the drag, which lessens my speed by 10%?" Answer: You will certainly care if and when speed, and more importantly the ensuing output of energy, is critical. But wait a minute. It is not the additional force which you need to apply to regain your loss in speed that matters. It's really the additional energy (work/time) you must apply to re-gain your 10% loss in speed. And that additional energy is indeed costly. The force required, for example, to push your fins, would be proportional to V2; BUT THE ENERGY YOU EXPEND IS PROPORTIONAL TO V3. This means to regain 10% in speed, you need to apply 33% more energy, i.e., (1.10)3. You may not care if you happen to be elevator diving in Cozumel. But when diving in waves, currents, offshore, and bad visibility, the resulting additional energy requirement can become a far more compelling issue. By the way, I am reasonably certain that the drag on today's diver can become considerably greater than the above example, when adding dry suits, integrated weights, etc. Experimental data is greatly needed. There is no doubt that when your energy output is critical, much of the so-called equipment that you are wearing to allegedly increase safety, is in fact, detrimental to your safety. (emphasis mine-DK) I do not have a problem with any diver making his/her choice to inundate themselves with equipment. However, the issue of equipment choice(s) and their use, which in truth are quite subjective, has become dogma. This does not speak well of the academic diving community. We have an opportunity to influence the dive equipment marketing and manufacturing industry, (not to mention AAUS rank and file), by doing what science and objectivity does best, and that is, have a strong, direct commitment to the fundamental issues, as opposed to the more mundane issues encountered by divers.
Posted by Dida at June 1, 2010 2:30 PM
