Presumption is the Mother of Disasters

Back in the early days of scuba, there were those who thought "Diving was dangerous and sex was safe." While I won't speak about sex, I will say that diving had some risks that don't exist today. R.P., a San Antonio (TX) diver, reminded us, "I started diving before dive vests and even before pressure gauges were standard. The tanks we were given in Cozumel were J-valve tanks, but no one was trained in J-valves. You can imagine what I did and saw."

For those who started diving in the late seventies, you might find it difficult to believe that a standard tank - a J-valve tank - had a lever that you had to pull to access the last remaining 500-700 psi in the tank (unless you dived with the lever down). Pressure gauges were uncommon. When it became hard to breathe from your regulator, you pulled the lever - hoping that it had not already been pulled inadvertently - and headed for the surface with the remaining air.

While it was easy to make a mistake with the J-valve, thankfully, they are history. But there are still plenty of mistakes left, so we asked our readers to tell us about mistakes they had made. We believe that if you share mistakes, you educate others, helping them avoid errors. It seems that many of the errors described are about running out of air, often because divers went in with tanks they had presumed to have been refilled but were not.

Running on Empty

David Ross, from Québec (Canada), told us that in 2008, when he had already made about 400 dives, he joined a liveaboard on the Great Barrier Reef. Upon arrival, he said, "I was tired already, tremendously excited, and preoccupied with preparing my complicated camera rig for the dive. On the first dive of day three, we went deep, roughly 100 feet. I saw a shark and tried to get my camera set for the shot when I felt that odd respiratory resistance sensation you get just before the tank runs out of air. I looked at my SPG, and I was O-U-T. I looked at my depth: 100 feet. OK ... In my rush to get in the water, I had not checked my tank. It hadn't been refilled - entirely my responsibility.

"My buddy was looking for me ... at 80 feet. By the time they saw me, I was pretty much at the surface. It was an uneventful ending with no complications, but I missed four dives the rest of that day sitting on the boat. I shared my example with all as a safety lesson as there was plenty of time for dinner discussion on the old liveaboard that week!"

Another common mistake is when a diver hits the water with the tank valve turned off. Often, it occurs because of an old habit of opening a valve all the way and then closing it a quarter of a turn, believing it will stop the valve from jamming in the open position. Some divers get confused between anti-clockwise (open) and clockwise (closed) turns and find themselves in the water with a tank with the valve open only a quarter of a turn. Their pressure gauge reads at full pressure before diving, but at depth, the air supply becomes inadequate.

After that happened to a diver living in London (UK), she told me, "Now I always use the mantra, righty tighty, lefty loosey!"

While I know I'm preaching to the choir, I will remind you that not only should you turn your tank on and ensure that your pressure gauge - or computer - shows a full tank, but your pressure gauge needle should not fluctuate when you take a couple of breaths before diving.

Failing to check your remaining air supply during a dive is also unforgivable, yet some divers still don't. Maybe it's simply complacency. David Bader (Norwood, NC) took responsibility for his error.

"While on a boat dive to a 70-foot wreck I had dived several times, I became complacent about checking my gauges. I usually ended the dive with 1300-1400 psi, so air was never an issue. On this day, after my first dive, I climbed on board. I had loaded two analyzed nitrox tanks and I immediately changed my gear over to the second tank and went to talk to some other divers. The deckhand was helping divers change their tanks, but I didn't notice that he also changed mine. But back to the tank I had used first. My buddy and I dove the wreck again, and I visited the engine room while my buddy swam around the deck. At 70 feet, I inhaled but got no air. My gauge read zero! I quickly swam out of the wreck to the top of the pilot house at 40 feet and searched for my buddy. He was nowhere to be found. Some other divers were 20-25 feet below me, but I decided it would be easier just to surface. I made it with no problem.

"When I returned to the resort, I downloaded my air-integrated computer data; my starting pressure was only 1320 psi for the second dive, the ending pressure for the first dive. That's how I knew the gear had been swapped back to the used tank. Had I even once checked my gauge during the dive, the crisis would have been averted."

Yes, one check would have solved the problem, but then again, as he knows, it's not incumbent upon a dive staffer who switches tanks to check and make sure it's a full tank.

Perhaps the recent popularity of air-integrated computers that display tank pressure contributes to his error, as the diver no longer has the readily available mechanical air gauge. Some divers may omit checking tank pressure before diving if their computers are scrolled to a different mode, such as the time or the nitrox mix. You can always have a mechanical pressure gauge as well, you know.

Of course, some divers make a second dive, knowing their tanks only carried the residual air supply from the first dive. That's asking for trouble.

Some divers carry a second smaller tank (a pony cylinder) with a redundant regulator for an out-of-air situation. However, it can lead to confusion, as Frank Goldsmith of Denver (CO) told Undercurrent.

"I do a lot of solo diving because buddies are often unreliable. Therefore, I carry a pony bottle with its own regulator, a spare mask, etc.

"I was on a dark night dive in the Solomons. We checked our equipment and back-rolled off the panga. About 15-20 minutes into the dive, at about 50 feet, it started to get harder to breathe. My gauges showed I still had 3000 psi. I didn't panic, but it was still getting harder and harder to breathe. The full tank was my clue that I'd put the pony regulator in my mouth and had been breathing down the pony tank the entire dive. I found my primary reg, switched over, and continued the dive, staying closer to the other divers.

"I had a different/custom mouthpiece on my primary, but I didn't notice on that dive Now I make sure I have my primary reg in my mouth before diving, even in the dark, and have my octopus and pony regulator where I can find them easily. Even after 2000+ dives, I learn every dive."

If you carry two regulators, they should look distinctly different. A brightly colored braided regulator hose on one will differentiate it from the other. And they should feel different, which is why FG attached different mouthpieces.

Losing Weight Pockets

Several divers describe how they lost weight pockets from their weight-integrated BCs during dives. Now that the accursed Velcro used to retain pockets been abandoned, BC manufacturers have introduced several ways to lock in weight pockets. However, divers must not be too casual when installing them on the BC.

K.S., a female diver from Denver (CO), said,

"My most recent diving mistake (as we've all made more than one) involved renting a BC in Roatan. I was confident that I knew the equipment since I had been diving for 30-plus years. We had descended to about 50 feet, and I felt unbalanced and shifted. Suddenly, weights started falling out of my pockets. I had not secured the integrated weight pockets. Fortunately, my two dive buddies reacted quickly - one held me in place while the other descended to retrieve my weights. After correctly attaching the weights to the BC, we continued the dive and had a great time. I now own a BC that I am familiar with. I always check my buddy's equipment and make sure they check mine. I'm more thorough and less in a hurry before jumping off the boat."

Many of the errors submitted to us could have been prevented with a thorough buddy check. Have we become so familiar with our dive equipment that we only perform perfunctory checks? Even solo divers can ask another diver to check their rigs before jumping in.

The Wrong Boat

In the past, we've heard from divers who, after their dives, climbed up on the wrong boat at crowded dive sites. Many boats look very similar, viewed from that angle, so we can forgive them if the boat has no obvious identification on its underside. It's not a serious diver error (unless you stay on the boat and go to another port), but it's embarrassing, and you can expect a bit of good-hearted ridicule, especially if you don't realize your mistake until after stripping off your gear and taking a shower!

Couldn't Make Up This One

I'm sure we've all seen divers - maybe us - enthusiastically make a giant stride off the boat before they realize they forgot to put on their mask (maybe while still wearing their glasses) or even their fins. That's not uncommon, but here's one we've never heard before.

A diver from Northern California told us, "An instructor who was an experienced lobster diver was diving alone, a common practice of charter boats that go to Santa Cruz Island. At a depth of 50 feet, he spotted a huge lobster in a shallow cave with a low overhang, making it impossible to reach the prize with his tank and buoyancy jacket on. He carefully removed the tank and BC, placed them outside the cave, took a big breath of air, and ducked under the ledge into the cave, quickly grabbing the big bull lobster with both hands. After a brief struggle. he backed out of the cave and immediately looked for the tank and BC, as he desperately needed air. They were nowhere in sight.

"Back on the dive boat, an alert divemaster saw a partially inflated BC with tank and regulator pop to the surface. The crew immediately launched a rescue operation. The lobster diver had rapidly ascended to the surface, still clutching the lobster but in considerable distress and having breathing difficulty and other dive related symptoms. He was evacuated by a USCG helicopter to a local hospital and fully recovered."

Of course, removing scuba gear to enter a cave is risky, but the diver failed to notice that his BC was slightly buoyant as he placed it outside the cave. The BC floated up to the surface, accelerating as it gained buoyancy when the air inside expanded.

Walking about at the surface on dock or boat wearing your weight belt can lead to trouble if you accidentally fall in, and casually handling an unfriendly octopus can lead to dramatic injuries from its sharp beak, both errors that were related by witnesses rather than the affected parties.

And our Northern California instructor friend has another story to tell.

"While diving in the Channel Islands, a new diver failed to notice a mild current and became separated from his buddy. He continued his dive alone until he ran low on air. He surfaced, inflated his BC, and began the long swim back to the boat across large kelp beds.

"Recalling his training in Monterey, he gently pushed the kelp down with his hands as he kicked slowly back to the boat. Eventually, he thought it might be a good idea to pull out his new dive knife and slash his way through the thick kelp. Back on the boat, the crew saw him swimming comfortably until they noticed him slashing back and forth with the knife like a marine sword fighter. Suddenly, a blast of air erupted from an air hose coming from his tank. He had accidentally slashed his low-pressure inflator hose in his exuberance to cut through the kelp. Everyone had a good laugh when he finally returned to the boat, but the technique will probably not be recommended in the future. We can say that good navigation will serve one better than a knife fight in the kelp bed."

Only his pride was hurt.

- John Bantin

Part II will appear in the October issue.