Do you ever get the feeling that the guys making up some of the rules for diving are the same geniuses that got fired from the M&M factory because they threw away all the “W”s? If that makes sense to you, then we have a cabinet post for you in the Ministry of Silly Diver Practices.
Here’s a classic. In the early 1970s, I was staffing an instructor training program and was evaluating several candidates who were demonstrating mask clearing technique. One guy launched into this discourse,”Roll over and blow air from your nose to allow the water to drain out the side of the mask.”
“But,” I queried, “wouldn’t it be easier to look up and drain the mask from the bottom where the water will be more naturally channeled?”
“No,” he quickly shot back. “I was trained to do it that way.”
“Well, why? Does it make any sense?” I countered in my best Socratic teaching style.
A funny look came over his face and he admitted he had never really thought about it, because his own instructor was an ex-UDT diver who knew everything. It turns out that his well-meaning mentor had taught him that way because he learned to dive on a double-hose regulator, and in order to clear the mouthpiece if it flooded, you had to roll on your side and get the exhaust hose to the lowest point. He was taught to clear his mask in that position because his instructor figured if your regulator had fallen out, then your mask might have gotten dislodged as well. The technique made sense in its era. But with the adoption of the single-hose regulator, equipment had evolved beyond what worked in the 1960s.
Inquiring minds might have some fun with a look at some of the more popular “Ten Commandments” in use today:
“Always be back on board the dive boat with a minimum of 750 psi” Why? Can you cash in that for credit at the air-fill Bank & Trust? Because we all now should know the significant benefit of safety stops, wouldn’t it make more sense to suggest arriving at the decom bar or or the anchor line at about 15 feet with 750 psi remaining? Then use the air for a nice 5- to7-minute safety stop? As long as you don’t completely drain the cylinder, there is no chance of getting water in it, and that’s more than enough reserve for a good hang and then to comfortably surface. Why waste 25 percent of your air? Use it underwater.
“Always put your weight belt on last” This is a holdover from when most horsecollar-style BCs had crotch straps, or tank harnesses were so complex that you had to be the “Lord of the D-Rings” to get adjusted. Most modern BCs have no crotch straps to potentially foul the weight belt, and the waist/chest strap is secured with a buckle riding well above the hips. I put my weights on first, and it makes donning the other gear far easier.
“Never put your mask on your forehead” Why do divers feel compelled to apologize for this benign and common-sense act? Sure, there are some circumstances when it’s not appropriate, like in surf entries, but in most situations it is a logical place to put the mask while resting on the surface or swimming on your back. An easy one-handed motion restores it on the face quickly and you’re back in business. Try that when your mask is pulled down over your neck. If you’re a no-neck ex-football player like me, that’s an exercise in self-strangulation. Who cares where you place your mask as long as you remain in control of it? Lighten up, please.
“You are properly weighted if you float with a full breath and sink slowly when you exhale at the beginning of a dive” Hey, anybody here ever heard of safety and/or decom stops? You want to be able to hover or maintain neutral buoyancy at the end of a dive to perform stops in the 15-foot depth zone. Your aluminum tank may gain as much as six pounds of buoyancy as the air is depleted. If you do your weight test with a full tank, you’ll end up hopelessly positive by the end of the dive. Make adjustments for neutral buoyancy with a nearly empty tank.
“Blow some air from your tank on your regulator’s first-stage dust cap” It’s a mystery to me how this practice ever got started. Why not just dunk the whole thing in the ocean since it has the same effect? When you crack the tank valve following a dive, there is a fairly good amount of salt water being trapped in the o-ring groove, which you immediately atomize into a wonderful salty grit forcibly coating the dust cap, then sealing that corrosive cocktail on your first stage. If you’re really concerned about cleaning, dip it in fresh water or lick it off before replacing. That also saves a lot of needless noise from sudden tank blasts that the harried boat crew thinks was a burst disc or blown o-ring.
“Always wear a snorkel on scuba dives” If you want to carry one in a pocket or on your leg, okay, but why would you want one attached to your head where it can distract you? Some snorkels these days are the size of nuclear exhaust chimneys and have sufficient drag to make you swim in a nice tight circle to the left. For a lot of divers, attached snorkels don’t allow the mask to seal comfortably, they tangle the hair, and several accidents have manifested when the snorkel instead of the regulator was placed in the mouth during an emergency. And remember, most modern BC’s are designed for surface swimming on your back, rendering a snorkel useless.
“You can’t dive if you have a beer with lunch” This is a real beauty of twisted logic. This is not aimed at abusive drinkers, whom we all agree should not be allowed to dive impaired. No, the scuba police want to save you from the hazards of dehydration that might make you more likely to get bent. All well and good, but consider for a moment that alcohol has the same effect on anti-diuretic hormone suppression as the caffeine in soft drinks, coffee and iced tea. And the effect of moderate consumption of these beverages is of little consequence anyway. So until the stormtroopers want to curtail the diving of everyone having a cup of Colombia’s finest over breakfast or the guy who knocks back a six pack of Coke routinely, I suggest that this may win the Medal for Pious Absurdity with Barley Hops Clusters.
“The best entry is a giant stride with an inflated BC” I guess it might make sense if you planned on bobbing around on the surface, but if your intent was to go diving under the water, why not just do a simple feet-first entry and continue right on with your descent? Most accidents manifest at the surface. It can be rough up there, and any surface wind or current tends to swiftly carry you away from the entry point. Say your good-byes before stepping off and get on with diving.
“Decompression diving is more dangerous than no-decompression diving” Sorry to burst the bubble (no pun intended), but this doesn’t measure up for several reasons. First of all, all dives are decompression dives because the ascent rate is factored in as part of the decompression, even on no-stop profiles. Secondly, divers can employ a wide variety of table or computer physiological models than will have different no-stop limits as a matter of proprietary design. The Navy tables use 60 feet for 60 minutes as a no-stop model, while some Buhlmann-based computer models use only a 44-minute exposure for the same depth. If the computer dictates a stop based on a square profile, can anyone seriously argue that a diver is more at risk given his conservative exposure by comparison?
Finally, if you run any decompression model up to its limit but stay just outside the required decom zone and ascend directly to the surface, you will find in most cases that diver will have more sub-clinical decompression stress (detectable by Doppler) than the diver who went ahead and planned a dive that required stops but allowed a more complete and thorough outgassing.
“You can’t get bent on one tank” With single cylinders available boasting volumes in excess of 200 cubic feet, you can now have the luxury of bending yourself several times on one tank if you like. Even with single 50-cubic-foot cylinders, I know dive guides who can get a couple of wall dives out of one and still have enough left over to blow up the flat tires in their rusted out jeeps.
We can see that a few sacred cows continue to moo long after their milk ran dry. A healthy dose of common sense goes a long way. If the Emperor wears no clothes or your dive guide seems to have neglected to don his intellectual wetsuit, then say so. We all benefit from a lively discussion.