March 2007

By Michael Ange

Q: I earned my first technical diving certification last year (decompression diving procedures). Problem is, I can't seem to find a place to use it. Any suggestions?

A: This is a common problem for tech divers and especially new tech divers as the vast majority of dive centers the world over are really only set up to handle open-water divers. It's a matter of numbers--there are more open-water divers, and it's both cheaper and easier for dive shops to cater to the masses. Adding to the problem is the fact that tech divers often require different sites, schedules, dive crew and topside support, and therefore don't mix well with a boatload of open-water divers. The good news is that there are a growing number of dive operators who are willing to serve the tech diving community.

Three that I know of include Divetech on Grand Cayman (offering a variety of tech diving services including deep wall diving); Southeast Oceanic in Dania Beach, Fla. (they can put you on a gorgeous wreck called the Hydro Atlantic with depths in the 140- to 200-foot range); and Dive Aquamarine on the island of Vanuatu (they dive the wreck of the Calvin Coolidge with depths ranging from 85 to 200 feet). For more suggestions from your fellow divers, you can also post your question on the dedicated tech diving forum of the Diver-to-Diver message board at www.scubadiving.com.

Another alternative is to join a group of like-minded technical divers and travel together. When you have a group, the economies of scale start to work in your favor. With the right numbers, operators are only too happy to set aside a dedicated boat, for example, and run according to your wishes. Ask around at your local dive shop, check with local dive clubs or visit diving message boards. Chances are there's a tech diving group near you looking for new members.

Just remember that even tech-friendly resorts and operators still have more open-water divers than techies to serve on any given day. If you're planning a trip with tech diving in mind, be sure to make your intentions known when you book. It doesn't hurt to follow-up ahead of your departure to make sure the operator can accommodate your specific requests while you're on-island.

Q: I have been diving since 1997 and have more than 100 dives logged, but I get very tired and usually abort the dive if I have to swim into a current. What can I do to be a stronger diver?

A: Many divers overweight themselves, and carrying around all that extra lead can quickly lead to overexertion, especially when swimming against a current. The first thing you should do is fine-tune your buoyancy. The easiest way to do this is to fully suit up in the gear you normally dive with, but use a tank with less than 500 psi. Now attempt to float at the surface with absolutely no air in your BC. Add or subtract weight in one-pound increments until you float slightly below eye level while holding a full breath but still sink slowly when you exhale. Try this exercise and you may be surprised at how much weight you can strip off your belt.

Carrying less weight will help, but what you need most is greater physical endurance, and there is only one way to get it--exercise. Any type of cardiovascular exercise will increase your physical stamina, but the best exercise for stronger finning is swimming laps in the pool, wearing your mask, fins and snorkel. Set a goal to swim at least 10 laps (500 yards). Ultimately, you need to be able to swim this distance nonstop, but until you get there, swim as far as you can, take a breather and go again. This isn't a race, so find your best sustainable pace and keep at it.

Q: Is there really an advantage to breathing nitrox instead of old-fashioned air?

A: The answer to the question depends on what kind of diving you're doing.

Let's review the basics: Air is a mixture of roughly 21 percent oxygen and 79 percent nitrogen. Nitrox, or oxygen-enriched air, is the term for any breathing gas with more than 21 percent oxygen and therefore less than 79 percent nitrogen. The concept behind nitrox is simple: If decompression sickness is caused by nitrogen, then less nitrogen in a diver's breathing gas is a good thing. A diver using 36 percent nitrox, for example, has 15 percent less nitrogen to be concerned about.

There are two ways divers can use this to their advantage. Many divers are attracted to nitrox because they can significantly extend their no-decompression times. For example, on an air dive to 100 feet you'll be limited to 25 minutes, according to the U.S. Navy Dive Tables. A diver breathing 36 percent nitrox, or EAN 36, can stick around for 40 minutes before exceeding his no-decompression limits.

Other divers, especially those with risk factors for DCS (obesity, dehydration, older age, previous DCS hits, etc.), will generally use nitrox for a physiological hedge against the bends. Instead of extending the length of their dives, they will dive according to air no-decompression limits and let the lower nitrogen content level the playing field for them a bit.

Got a question you need answered?
E-mail it to edit@scubadiving.com, or write to Ask An Instructor, 6600 Abercorn St., Suite 208, Savannah, GA 31405.