January 2001

By John Francis

Case 1--DCS: What? Me Worry?

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George, 38, has been certified for 16 years and still dives nearly every week. Constantly in search of more bottom time, he begins pushing the no-deco limits, cutting planned deco stops short, making faster ascents and skipping safety stops. He justifies this with the belief that dive tables are designed for average divers and include a generous margin of safety. Because he is a relaxed, skillful diver with an unusually high level of physical fitness, George believes he is especially resistant to DCS. He points out that he has never been "bent."

• No one is immune from DCS.

• Keep a margin of safety between you and your predicted no-deco limit. Increase the margin on repetitive dives, and as you get older.

• Always make a slow ascent and a three- to five-minute safety stop. Consider this your personal margin of safety.

• Exercise regularly to improve, or at least maintain, your ability to meet unusual physical demands like waves and currents.

• Choose your diving to suit your physical abilities. Recognize that some types of diving require more strength and stamina than others.

• If you become exhausted, stop, rest and--if necessary--bail out of the dive.

• Planning your dive includes coming to agreement on what you will do in case of separation. When diving with a buddy, planning means explicit communication.

• A buddy relationship entails duties to the other diver, even though the relationship is forced on you. You can decline those duties only before the dive begins.

• Regulators should be serviced at least once a year; more often if used frequently or in harsh conditions.

• Packing for a dive trip should include detailed inspection of all your dive gear, so cracked straps and corroded fittings can be fixed before they cause trouble.

• Introduce only one piece of major new equipment at a time. Perhaps take a dive or two to familiarize yourself with a new BC before starting to use a new camera. Or decline your friend's offer of the BC.

• If you haven't been diving for a while, it may be best to take nothing new on the first dive. Use this one to fine-tune your buoyancy and reacquaint yourself with your equipment.

• Struggling with new equipment causes stress. So do cold, depth, current and low visibility. When environmental factors will make the dive difficult anyway, don't compound your problems with unfamiliar equipment.

• A rapid or out-of-control ascent increases the risk of embolism. Forget your camera, flare your arms and legs and keep your airway open.

• Dive within your training and experience.

• Take responsibility for your own safety.

• The time to intervene in a series of cascading problems is early. Perhaps a leaking O-ring alone should be enough to abort a dive. Certainly a delayed entry, separation from the dive guide and no wall where you expected it to be is enough. In any event, when in doubt, get out.

• Use your compass. Orient the dive site to the compass before entering the water so that if you have to make a search you will have a pretty good idea which way to go.

• A buddy check should be complete, from mask to fin, because small problems can escalate into bigger ones.

• The obligation to check your buddy's gear does not end on the boat before the dive. And it doesn't end with an in-the-water gear check. You should continually monitor your buddy and his equipment throughout the dive.

Today's first dive is actually conservative for George, a wall dive to 110 feet within no-deco limits. The dive goes smoothly, and with many colored sponges to look at on the way up, George makes a fairly slow ascent. As usual, however, his "safety stop" at about 15 feet is no more than a brief pause. Thirty minutes after reboarding the boat, George suffers a massive central nervous system DCS hit. Fortunately, air evacuation to a recompression chamber is rapid, and George makes a full recovery.

What George Forgot
Recreational dive tables and computer algorithms are estimates of DCS probabilities, not guarantees, and not all the causes of DCS are known. Because of that uncertainty, a safety margin is needed, which George was using up with his fast ascents and short stops. Finally, the odds caught up with him. Perhaps George was dehydrated this morning. Or tired. Or cold. Certainly, he is getting older. All these factors are known to increase the risk of DCS. Or perhaps some other factor not yet understood made today George's unlucky day.

What You Should Remember

Case 2--Out of Practice, Out of Shape

Ralph, 42, certified for 12 years, used to dive from the beach almost every weekend, but job and family have severely reduced his bottom time in the last five years. When his old dive buddies propose getting together for another beach dive, he agrees enthusiastically.

Ralph finds that carrying his gear to the beach and suiting up is more work than he remembers. His wetsuit seems to fit more tightly--can it have shrunk? By the time Ralph enters the water, he is red-faced and puffing. The waves seem bigger than he remembers, too. One staggers him, and he recovers his balance with difficulty. He fails to duck completely under the next wave, and is tumbled up onto the beach, exhausted. Wisely, he decides to sit out the dive.

What Ralph Forgot
Physical fitness is an essential element of your readiness to dive, and it declines with both age and inactivity. Ralph's more sedentary lifestyle made him less able to cope with the physical demands of diving. Enthusiasm for this reunion dive, and perhaps peer pressure, led him to attempt too much.

What You Should Remember

Case 3--Your Buddy: Friend or Foe?

Jason, 32, has been an active diver for eight years. He normally dives solo and believes strongly in each diver's need to be responsible for his own safety. He maintains his equipment carefully and carries appropriate safety equipment, including a pony bottle.

On an out-of-state trip, he books a dive with a local boat. The divemaster insists that Jason dive with a buddy, and pairs him with Art, another diver on the boat who is a stranger to Jason. Early in the dive, Jason and Art become separated. But the dive is shallow, the water clear and calm, and Jason assumes that Art has merely gone his own way. He continues the dive in the solo mode he is accustomed to.

After 40 minutes, Jason returns to the dive boat, only to meet hot stares and cold shoulders. He discovers that Art, on losing contact with Jason and not finding him after a brief search, has aborted his dive and returned to the boat to report that Jason is missing. Divemasters have been searching for Jason with increasing anxiety, which now turns into anger.

What Jason Forgot
Both Jason and Art failed to plan their dive. Especially, they failed to make clear what each diver would do if they became separated. Art followed standard procedure, which requires a diver to treat separation as a possible emergency: To surface and report if he loses his buddy and cannot find him again. Jason did not. If a buddy team is to become a pair of solo divers, both divers must agree to it before the dive begins.

What You Should Remember

Case 4--Bad Gear Equals a Bad Dive

Melinda, 42, has not been diving in the year previous to this trip to Cozumel. In the rush to clear her desk before her vacation, she failed to have her regulator serviced, but it is a high-performance one that has always worked flawlessly.

Upon reaching a depth of 60 feet on her first dive, Melinda's second stage begins to free-flow violently. Banging it with her hand and pushing the purge several times fail to stop the free-flow. Melinda aborts her dive, and misses the day's second dive as well while her regulator is being repaired.

What Melinda Forgot
Regulator performance degrades with time, even if the regulator is not used or is rarely used. As important as it may have been to Melinda to finish her work before her dive vacation to Cozumel, her life may depend on whether she has also taken time to inspect and service her dive equipment.

What You Should Remember

Case 5--Doing Too Much

Randall, 28, has been diving for seven years. He has become interested in underwater photography, and on this trip to the Cayman Islands will be trying out a new camera system, complete with strobe and macro lens. Just before leaving, a buddy offers to let him borrow his new back-inflation BC, a style Randall is eager to try out, so he agrees.

On his first dive, at 90 feet along a wall, Randall is intent on adjusting his strobe arm and camera settings and doesn't notice that he is slightly buoyant and beginning to ascend. By the time he realizes it, he is passing through 70 feet and gaining speed. He quickly reaches for the BC's oral inflator but, momentarily confused by the unfamiliar controls, pushes the wrong button and adds air instead of dumping it. With his ascent out of control, he pops to the surface. But Randall is nevertheless very lucky: he escapes injury and even maintains his grip on his camera.

What Randall Forgot
By diving with several pieces of major equipment that were unfamiliar to him, Randall risked task overloading. The unusual concentration required to master his new camera system left him paying too little attention to how his BC worked, much less to his environment and his buoyancy. His depth may have contributed to the problem if some nitrogen narcosis was present--always a possibility below 60 feet. It certainly increased the risk.

What You Should Remember

Case 6--Blind Faith

Patrick, 33, has been diving for seven years, mostly for game and scallops in California's kelp beds. He makes his first dive trip to the Caribbean when Bill invites him to take the place of another diver who became sick at the last minute. For Bill, one of the highlights of the trip will be a dive on a famous wreck. In fact, Bill and his original buddy had taken a wreck diving course to prepare themselves.

Though Patrick has never made a wreck dive or been trained in wreck penetration, he feels obligated to accompany Bill on the dive. "Bill seems to know what we"re doing," he says to himself. "I"ll follow him."

The wreck has been partially opened up for easier diving, but when Patrick follows Bill inside, he is surprised at how cramped and dark it is. He has trouble adjusting his buoyancy and overcompensates, frequently bumping against the sides and the ceiling of the compartments. Just as Bill's fin tips disappear into the next compartment, Patrick's fins stir up a cloud of silt. Unexpectedly blinded, Patrick becomes disoriented. Now approaching panic, he gropes wildly for an exit but has no idea where it is.

Fortunately, Bill realizes they have become separated, and returns to the previous compartment. He hears Patrick's rapid breathing and scraping of the walls. Reaching into the cloud of silt, he feels Patrick's shoulder and is able to pull him through the opening to a larger compartment that is lighter and open to the outside. Patrick begins to calm down, but both decide to end the dive and surface.

What Patrick Forgot
Patrick made several mistakes, the most serious of which was to be a dependent buddy, to abandon responsibility for his own safety and assume Bill would be able to take care of him. Rather than disappoint Bill or look like a "chicken," he made a dive he was not prepared for.

What You Should Remember

Case 7--Wall to Wall Trouble

Charles, 52, and Emma, 48, have been diving together for 13 years. They are vacationing at a popular Caribbean resort, and today are doing a wall dive with 12 other divers. The boat moors in 50 feet near the top of the wall and, though visibility is not good today, the boat captain, who doubles as the divemaster, tells the group that the wall is directly below the boat.

All the divers enter the water and descend in a group. Charles spots an air leak from Emma's first stage, probably a bad O-ring. They surface together to change her tank, and after five minutes re-enter the water. They don't realize that while they were changing Emma's tank, the dive boat has swung on its long mooring rope, and is now over deep water.

Charles and Emma descend below 60 feet without finding the bottom or the wall. All around them is a blue-green haze, with visibility about 30 feet. They guess the direction of the wall and start finning, but in fact are moving away from the wall. After finning a few minutes without finding it, they reverse direction. Both are becoming fatigued and Emma, who is following Charles, falls farther behind.

After a while, Charles glances back but can't see Emma. Alarmed, he searches in a circle but still can't find her. He surfaces rapidly and finds Emma on the surface, unconscious. The dive boat is more than 200 yards away, up-current, and does not respond when Charles yells and waves his arm.

When they are finally recovered, Emma is dead. The cause is listed as drowning, probably resulting when Emma became exhausted, over-breathed her regulator, panicked and lunged for the surface, swallowing water on the way up.

What Charles and Emma Forgot
Often a small problem leads to larger ones, causing an emergency far out of proportion to the precipitating event. In this case, a leaking O-ring led to a delayed, out-of-position entry, which led to the decision to look for the wall instead of surfacing. By this time, Charles was so intent on his search that he neglected to check his buddy. Trying to keep up with the faster Charles, Emma became exhausted and demanded more air than her regulator could deliver.

What You Should Remember

Case 8--Buddy Check

Roger, 32, has been diving for six years. Standing at the entry door, he puts his feet into his fins, snaps the straps over his heels and makes his giant stride--just like he has done scores of times before.

This time, however, he fails to pull one strap high enough and it slips under the heel plate of his fin. He and his buddy exchange OK signs and descend. This is a drift dive, and the two float with the current until the divemaster signals the group to gather behind a large coral head. While Roger tries to fin out of the current, his unsecured fin comes off. Despite kicking desperately with the other fin, he is carried away by the current. Fortunately, the divemaster sees Roger's problem, swims to him, and helps him make a safe ascent.

What Roger Forgot
Both Roger and his buddy neglected to check each other's gear carefully, not only on the boat while suiting up, but again in the water before descending. Roger forgot to be as careful about seemingly minor things like fin straps as he was about his regulator.

What You Should Remember

10 Safe Diving Tips

1. Maintain your gear. Check it before the dive trip, and before the dive.

2. Be physically and mentally fit. Strength, endurance and aerobic conditioning are all essential to safe diving and all decline inevitably unless you maintain them with exercise and good diet. Mental fitness includes control of stress and anxiety, and developing confidence in your skills. Begin your dive rested, warm and hydrated.

3. Dive within your training and experience. Unusual depth, cold water, high currents, low visibility and restricted overheads all present unique challenges. Yes, you'll learn by doing, but get special training first.

4. Plan your dive, dive your plan. Visualize potential problems and map out responses. Agree with your buddy on comfortable limits of time, depth, swimming direction and hand signals.

5. Watch your gauges, keep a margin of safety. Even if you know your air consumption rate, unusual combinations of depth, current and exertion can surprise you. Use the green/yellow/red zones on your computer as approximate indications, not absolute. Use less of the green on repetitive dives.

6. Breathe continuously, deeply and slowly. Fatigue and panic can elevate your breathing rate to levels your regulator can't support. When either appears, it's vital to stop, calm down, breathe slowly and, if necessary, get to the surface.

7. When in doubt, cancel the dive. The best way to prevent minor problems from snowballing into life-threatening emergencies is to abort the dive immediately. Likewise, if you feel in your gut that today's dive is beyond your capabilities, have the courage to opt out.

8. Ascend slowly, stop near 15 feet. A slow ascent rate (about 30 feet per minute) and a safety stop for at least three minutes at about 15 feet are the best ways to cut DCS risks.

9. Accept responsibility for your own safety. Your role in the buddy team is to be able to help your buddy, not to rely on your buddy to help you. In fact, if you don't think you could make a dive alone, you shouldn't make it with a buddy.

10. Have fun! Remember, that's the point of all this. If you're cold, tired or something just doesn't feel right, don't do it. Concentrate on what you like about diving, and cultivate the joy. Your enthusiasm will make you more confident and safer.

Dive Safety by the Numbers

Question: Which group suffers the most dive accidents: The nervous newbies or complacent old salts?

Answer: It's a tie. According to the latest available stats*:

Depending on gender, divers with basic scuba training account for 35 to almost 50 percent of accidents, while advanced certified divers account for about 40 percent.

So what do these numbers mean? Maybe a lot, maybe very little. As DAN points out, "time since initial training is not necessarily a good measure of diving experience or current ability." And the stats may be influenced by other factors: Experienced divers tend to be older and more susceptible to cardiovascular disease, for example, or they may be attempting more difficult dives.

Bottom Line: Complacency about the risks of diving, at any skill or experience level, may be the biggest risk of all.

* Source: Report on Decompression Illness and Diving Fatalities: 2000 Edition, Divers Alert Network. Covers 1998 accidents. The 2001 edition is available from DAN by calling (919) 684-2948.

The Safety Routine: How to guard against getting too relaxed and forgetting safety.

Try a checklist. Pilots go through detailed checklists before every take-off for a good reason: If it's written down, and must be checked off, you're not likely to forget it. Planning a dive against a checklist ensures that, for example, you and a new buddy remember to agree on hand signals.

Develop a routine. Always doing things the same way, in the same order, helps prevent dumb mistakes. Always packing your gear in the same order, and always dressing in the same order, for example, makes it less likely that you'll forget something.