The Natural Selection of Rebreathers
By Donald Tipton
It was a wonderful day. Flat seas and clear skies greeted us as we passed the point and moved offshore. I had recently been certified on the Dräger Dolphin rebreather and was curious if the bubbleless breathing device would make a difference in photographing dolphins. Normally I would freedive, as dolphins are not always fond of scuba bubbles, but freediving has its limitation—me.
I slipped quietly into the water as I have done with marine mammals thousands of times before. It quickly became clear that not only was my presence accepted by the dolphins, they seemed fascinated with the strange equipment on my back. They would come in close to echolocate in order to get a better sound picture of the rebreather.
As my model descended, things only became more interesting. Soon, the dolphins started rushing back and forth between the model and me, as if we were part of a new game.
When you freedive with dolphins, the window of opportunity for composing an image is painfully short. Now I was able to wait for the magic to happen, instead of rushing off to the surface for a gulp of air. My only concern at this point was that I might prematurely run out of film. Sure enough, that’s exactly what happened!
My experience with the dolphins and the rebreather that day has changed the way I shoot. It has opened new photographic possibilities that I have yet to fully explore. However, there is a price to pay for this bubbleless advantage. The gear is more difficult to handle when traveling, and gear prep and clean-up is a bit more time consuming. But, at the end of the day, I’ve found it to be well worthwhile.
As the name might imply, the rebreather collects the exhaled gas from the diver, removing the CO2 so that the gas may be re-breathed.
Rebreathers come in two basic types, closed circuit and semi-closed circuit. Closed circuit rebreathers recapture nearly 100 percent of the breathing gas, but require sophisticated electronics to monitor the level of O2 being supplied to the diver. Semi-closed models avoid this by periodically supplying more fresh gas to the system than is required. This creates an occasional discharge of bubbles, but still far fewer than regular scuba. Semi-closed rebreathers are by far the most popular for sport divers.
Rebreather training is available from many dive training agencies. Since all rebreathers must use a gas higher in oxygen content than air (if you tried to re-breath air, you would quickly run out of O2), training usually starts with a course in nitrox.
In addition to the use of nitrox, the gear must be assembled in a specific order and then tested for a number of parameters. After the dive, the rebreather must be disassembled, washed and hung-up to dry, because retained moisture in the breathing loop produces unpleasant bacteria.
Training also includes self-rescue techniques. Most rebreathers include a backup gas open-circuit regulator that can be used in an emergency. As long as the diver is disciplined in set-up and maintenance of the rebreather, there should never be any problems.
Higher Cost for Equipment
Rebreathers, like cars, come in a variety of styles and prices. Sophisticated models capable of tek-diving depths can cost upwards of $15,000. But models developed for sport diving can cost less than $2,000, a little more than a high-end BC and regulator.
If it’s important to you to get closer to mother nature’s most enchanting sea creatures—especially those that are normally exhaust bubble-shy—then it might be worthwhile to check out the new world of rebreathers.