April 2007

By John Francis

Like scuba diving itself, wreck penetration isn't especially hazardous if you know what you're doing, but it can kill you if you don't. Those who do it regularly are pretty clear on one thing: If you're interested in wreck diving, don't try to figure it out by yourself, or think you can learn it from a book, let alone a magazine article.

If you plan to penetrate the interior of a wreck, you should first take a wreck diving course. Nothing can substitute for the instructor's "No, you've got it backwards."

There are two kinds of penetration diving courses:

• Technical (or "full-penetration") courses assume familiarity with mixed gases, gas switching and planned decompression stops, and are not the place to start.

• Recreational (or "limited-penetration") wreck courses begin with the open-water skills you already have. You'll learn how to handle the unique hazards of wrecks, you'll practice using lines and reels and, if all goes well, you'll make a limited penetration of a wreck, staying within the zone of ambient light near large swim-through openings.

Course Prerequisites

Are you ready for this? When you show up for that first wreck-dive class, the instructor will expect to see:

• Pinpoint buoyancy control. "Buoyancy control is extremely critical inside a wreck," says Sean Harrison. He's vice president of training and membership services at SDI, and has taught many wreck diving courses. Inside a wreck, you may have to maintain your altitude to within a foot or so, maybe even inches, to pass cleanly through an opening or avoid scraping the overhead. Easy? Maybe not. "I think the buoyancy-control issue is going to be the biggest surprise for most divers taking a wreck course," says Bill Stone, of Orlando, Fla. It was for him when, with several specialty courses and more than 100 dives in his log, he took a wreck course in 2005. "When you're swimming outside a wreck, you think your buoyancy control is great because you can follow the deck line exactly by finning forward. But once you challenge someone to go inside a confined space and not touch the top or the bottom, inevitably it's a different story."

• Trim control. "In wreck diving, it's key to be horizontal," says Steve Martell, PADI's vice president for training and quality management. Your fins may even need to be higher than your head to keep them away from the floor where they could stir up silt.

• Deep-dive certification. Many wrecks are deeper than 60 feet, because shallow wrecks are removed as dangers to shipping. If you get certified for the 60- to 130-foot range before you take the wreck course, you'll be able to train on the kinds of wrecks you'll probably want to dive on.

• Night or low-vis experience. Even in the ambient light zone (illuminated by sunlight coming through openings in the wreck), it is still darker inside. Are you going to be comfortable? Night-dive experience answers that question and gives you a head start on using lights.

• Air-management skill. "You've got to realize that if you're inside a wreck and suddenly decide you're low on air, you can't just go straight up," says Harrison. "That option doesn't exist." So you need to develop the habit-the discipline-of monitoring both your pressure gauge and your breathing pattern more consistently than is common in open water diving.

• Maturity. "Maturity is not just a matter of age," says Harrison. "Is the diver looking ahead and seeing everything that's going on around him, anticipating problems? That comes from diving experience. I wouldn't say 100 dives is a prerequisite, but if you've made 15 or 20 recent dives and your buoyancy control is getting better, you're probably ready to learn wreck diving."

On the Wreck

Any penetration of a wreck will be preceded by an external survey to get an overall picture, assess the hazards and identify likely entrances and exits. You may need to make several dives on the outside of a wreck to see, literally, what you're getting yourself into before you go inside.

Often the wreck is deep, invisible from the surface and surrounded by blue water. You'll want to descend and ascend on a line, either the anchor or mooring line or a buoyed line attached to the wreck.

Hazards in and around wrecks include:

• Suction. It's generated around openings in the wreck by current and surge. Even when there is no suction, a current is likely to accelerate along the side of a wreck. Approach openings cautiously and from a distance.

• Entanglement. Wrecks attract fish, fishermen, nets and line. If you feel yourself caught, stop. Turning around to see what the problem is will likely make the tangle worse. Reach behind your head to feel for the offending line. Signal your buddy for help.

• Collapse of weak structure. You don't have to go inside a wreck to become trapped under falling debris. Especially when wrecks lie on their sides, superstructure, masts, cranes and other objects can lean outward over your head. None of it is designed to be stable in that position; all of it is deteriorating, and today could be the day it falls down. Avoid swimming underneath anything and avoid touching, even if the structure looks solid.

• Abrasion and cuts. The most common wreck injury, says Martell, is a cut or scrape to your skin or your gear. Wear gloves and a full-length exposure suit.

• Disorientation. Wrecks often don't look like ships or anything else familiar. Especially on larger wrecks in poor visibility it's easy to get lost and, more important, be unable to find the ascent line. On a steel wreck your compass won't help either; iron deflects the magnetic compass card.

Fortunately, wrecks usually have many distinctive features that lend themselves to "natural navigation." Before you leave the ascent line, look around for something close by you can recognize: a capstan, a ventilator, a hatch cover. As you leave it, try to remember a "bread-crumb" trail of other features you can follow back to the line. Sketching your route on your slate is itself a memory aid. If visibility is really poor, you may need to lay a line as you swim away from the ascent line.

Penetrating the Wreck

In a limited-penetration wreck course, you'll enter the wreck with a buddy, under the supervision of an instructor. With your buddy's help, you'll lay a line as you go and then turn around and retrieve the line as you exit. The reel man is first in, last out (see "Laying a Line").

The interior of a wreck has all the hazards of the outside in heightened form. Because you're in a confined space, the chance of getting caught or cut is greater. In passages that twist and turn, sometimes at crazy angles, it's easier to get lost. Under structure, collapse is always a danger. And it's darker. Then there are new problems inside a wreck, like:

• Siltout. Silt-fine sand and rust particles-collects inside every wreck, and if stirred up by a diver, it can shut down visibility to zero. In moments you can literally be diving blind. It settles on the floors of compartments and also clings to the overhead, from which it can rain down if disturbed.

When you first enter, look up to see if your bubbles are dislodging silt. Be precisely neutral and trimmed horizontally so you don't accidentally contact the ceiling or the floor. Go slowly, using a frog kick or a "modified flutter." Martell describes it: "Imagine your body horizontal but your knees bent so your fins are above your head. Now you can make small, mini-flutters that don't stir up the silt on the floor." If a siltout occurs, stop a minute or two. While you take a deep breath, the silt may settle. If it doesn't (maybe even if it does), it's time to get out. Follow the line but don't pull on it, as you might cut it or pull a wrap loose. Don't rush; you'll just stir up more silt.

• The roof over your head. Under any overhead, there's the risk that direct ascent to the surface is not possible. If you lose your air supply, you'll need to get out before you can go up. Or, if you lose your weights, you may be pinned to the ceiling and unable to get out.

To avoid running out of air, have a redundant air source (a pony bottle) and follow the "rule of thirds" for turning the dive. That means using one-third of your air supply going down to and into the wreck, one-third for going out and up and keeping the other third in reserve. Turning around with two-thirds of your gas supply remaining and carrying a separate pony bottle give you more time to get out so you can go up.

• Panic. Probably the greatest danger on any dive, panic is especially a threat here because most of us, even if we don't feel claustrophobic, have more anxiety in a confined space, and that puts us closer to our panic threshold. If panic does occur, the result can be catastrophic.

To prevent anxiety turning into panic, always dive with a buddy you know and trust, and push the envelope of your experience gradually. Resist the temptation to go from one compartment to the next to the next, each a little darker than the one before.

Wreck diving, like open-water diving, is a mental discipline even more than it is a set of skills or a physical challenge. Keeping your head, taming your emotions, remembering your training and using good judgment are the essential elements of safe wreck diving.

Laying a Line

See illustration on the right.

Most instructors introduce the line and reel on land. You and your buddy will walk the parking lot, paying out line, tying it off and reeling it in before you try it in the water. There you'll practice several times on the outside of the wreck before you take your new skill on a penetration. Here's the drill:

The first step is the outside tie-off. Find something solid, without sharp edges, and with a fair lead into the passage or down the deck. Various knots are used, but the best is to have a loop at the end of the line big enough for the reel to fit through. Pass the loop around the tie-off point, pass the reel through the loop and pull it snug. It can't come untied and another diver can't untie it by accident.

Next, into the wreck. If there are two divers, the one with the reel goes first and the buddy follows. Just inside, the reel diver makes another tie in case something does happen to the first tie. Then he lays line to the first wrap, or intermediate tie-down point, maybe 50 feet later. The buddy helps by directing his light, keeping the line taut, pulling it out of "line traps"-cracks or tight spots the line could be pulled into-and making sure that wraps are secure. The line should be laid low and always on the same side of the passage so divers don't have to cross it; crossing carries the risk of tangling with it. At the end of the penetration, the reel diver makes the final tie-off. He locks the reel, takes several wraps around a solid object, then several wraps around the line itself, and clips the reel to the line.

Exiting is the reverse except the buddy goes first while the reel diver follows. He reels up the line, spreading it across the reel so it doesn't bunch up at one end and jam. The buddy removes wraps and keeps the line taut.