EDITORIAL, JUNE 2010: WHERE THE BUCK STOPS

By Alex Brylske

I dive off charter boats frequently, so I have lots of opportunities to observe divers. I see good divers and bad, experienced pros and neophytes, and locals as well as tourists. With such variety, it’s tough to draw any uniform conclusions. But there does seem to be a trend and, from my vantage point, it’s not a good one: My admittedly unscientific assessment tells me that divers are assuming less and less responsibility for their own well-being. In fairness, it’s not really restricted to divers; it’s been a societal trend for some time.


When something goes wrong the answer is to blame anyone but ourselves. Abandoning responsibility even happens when nothing goes wrong, as I saw on a recent dive.

EDITORIAL, MAY 2010: ISN'T IT TIME?

By Alex Brylske
Photo by Joseph C. Dovala
(Readers, please comment at bottom of editorial)

Unless you were on some other planet recently, you no doubt heard about the recent event at Orlando’s SeaWorld in which a trainer was killed by an orca. Clearly, it was a tragic situation made worse in that it was apparently a very public spectacle. And unlike what was initially reported by authorities, the victim did not fall into the pool, but was grabbed and dragged into the water by the whale. Some were surprised that the animal wasn’t put down, as would have been the case with a dog; and many even expressed alarm when it was made public that this was the third fatality involving the whale, Tilikum. (Although, in fairness, it’s far from certain that he was the cause of one of those deaths.) Personally, I was heartened to learn that Tilikum wasn’t euthanized. It also made me question the purpose and true cost of turning marine mammals into circus performers.

NO DUMB QUESTIONS, MAY 2010: A PHYSICS PRIMER FOR SCUBA DIVERS

by Alex Brylske
Photo by Joseph C. Dovala
Readers please submit comments at the end of the article.

Q: Al Pinzon had a question about tank capacity. “My wife and I are recently certified Open Water divers. I use an 80 tank and my wife uses a 50. Our question is how do we know exactly how much air is left in our tanks at the conclusion of a dive? Even though each of our submersible pressure gauges (SPGs) may both read 500 psi, we know we don’t have the same amount of air. So how do we determine the amount of air left in the smaller tank so my wife doesn’t risk running out of air?”

A: There’s a very simple way to convert psi to cubic feet. Just take the capacity of the cylinder in question and divide it by its maximum working pressure. The product is, in essence, how many cubic feet of air is accounted for by each “psi.” Let’s take the standard 80-cubic- foot cylinder as an example. By dividing 80 (its maximum capacity) by 3,000 (its maximum-rated pressure) we get 0.0266. In other words, we can assume that each psi of pressure accounts for 0.0266 cubic feet of air. Thus, if the tank is filled to only 2,000 psi, rather than its maximum 80 cubic feet, it contains only 53.2 cubic feet (2,000 X 0.0266).
In the case of your wife’s 50-cubic-foot tank, the value is 0.0166 (or if she uses the more standard 63 cubic footer it’s 0.0210). Therefore, if you each end your dive with 500 psi remaining, you have 13.3 cubic feet of air left but your wife has only 8.3 cubic feet.

Of course, even though your wife would have less air remaining, it’s likely she also uses less air, which is why you can both plan to exit the water with 500 psi. So, with all things being equal, you’d both have about the same usable reserve in terms of time underwater at the same depth.

More questions after the break...