2000-12 Hanging Around: Beating Deco Boredom
By Karl Shreeves
What a boring dive.
OK, it wasn’t all that boring. Actually, it was pretty exciting. Nothing boring about pushing deep into a cave, almost 1,000 feet back and 300 feet down. That part was a heart-pounder. There’s nothing like watching your stage bottle SPG drop 500 psi every two minutes to kick in the old adrenal gland.
But that was then. After 20 minutes on trimix 10.5/50 (10.5% oxygen, 50% helium, balance nitrogen), our team headed up with two hours decompression ahead of us. That’s two hours of sitting underwater breathing while excess nitrogen and helium finds its way out of our tissues.
At first, deco went quickly because the first stops were short, two to five minutes, and we were switching gases (going to different gases as you ascend gets the helium and nitrogen out faster). It all tends to go by relatively fast until reaching 30 feet. That’s 15 minutes. The next stop was 17. At the last stop, we had—yawn—30 minutes to hang before surfacing. The support divers hovered around us with a look that asked, “Are we having fun yet?”
No, we already had fun. Now we’re paying for it.
What Do You Do When There's
Nothing To Do
Of all the things non-tekkies ask about tek diving, one of the most common questions is, “what do you do during all that decompression?”
The answer depends on the situation. If you’re decompressing while drifting under a lift bag, the only thing that keeps you at your stop depth is your buoyancy control, so you spend the whole dive watching your gauges and controlling your depth. It passes the time, but it’s not very relaxing.
Hopefully, as with cave diving, you have some place you can sit or hang in order to relax. Then you spend your time doing the following:
1. Staying unbent. Your first order of business on a long hang is staying healthy, so you spend a lot of time confirming your deco schedule, making notes and checking pressure gauges, bottom timers and computers. If your total decompression is less than 90 minutes, this pretty well takes up all your time.
2. Practice, practice, practice. If you’ve got more than 90 minutes hang time, and you’re situated so you can maintain depth without watching your gauge constantly, the next order of business is to practice emergency drills. Practice valve shutdowns, retrieving emergency gear and determining contingency decompression schedules.
3. Pause for refreshment. Your DCS risk goes up when you’re dehydrated, at least in theory, and two hours of breathing dry gases and using your drysuit’s urination plumbing doesn’t help. The solution is having bottles or pouches of water or fruit juice waiting for you. Some divers even eat during decompression, but personally, I restrict underwater intake to fluids. If I choke on Powerade, I can cough it out through my regulator. If I choke on food, it would take more than a good Heimlich maneuver to keep me out of trouble.
4. Good humor and games. Tek divers carry multipage slates, and most people think it’s because of all the important data and communication required. Actually, that accounts for maybe 3 of 12 pages. The rest gets used for messages like, “Three drunk penguins walk into a brothel and…” or numerous games of hangman. For really long decos, I have a magnetic travel chess/checkers set drilled with holes so it sinks. Of course, if there’s any current, the pieces blow away because the magnets aren’t very strong. (The guy at Toys R Us says I’m his best travel chess customer.)
5. Feed the mind. Finally, you can read. Magazines hold up pretty well, if you’re careful, and so do paperbacks. Of course you will never actually finish reading an entire book and once you soak a paperback, as soon as it dries it becomes a brick that tears apart if you try to open it. So, you either buy two copies so you can finish it topside later, or, you only read it underwater. This works because on the next dive, you take the brick down with you and leave it at your 20-foot stop with your oxygen cylinder. By the time you get back to it, it’s nice and soggy so just flip to where you left off.
We badly need dive computers with “game mode” for long decos. Sound far-fetched? My cell phone has games—so why not a dive computer? They could design it so the computer pauses the game and shows you time, depth and other info automatically when needed and at regular intervals.
The main thing would be to not confuse your high score with your deco time.
Karl Shreeves is VP Technical Development for DSAT and PADI.