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Freedom and Safety

The underwater realm holds a special place in the hearts of divers around the world. Throughout history we have been drawn to the water. As technology has advanced, so has our capacity for discovery and adventure. Currently, scuba (open circuit) tanks and regulators are the most common devices of choice in the recreational diving world. Closed circuit rebreathers are the next evolution in recreational diving.

Scuba (open circuit) diving is not a very efficient use of breathing gas (air). Even though very little oxygen from each breath is actually used by the diver’s body, the entire breath is vented into the water.

With a CCR (closed circuit rebreather) the breath of gas is not vented into the water but remains in the breathing loop. After the breath is exhaled, it travels through a scrubber where the CO2 (carbon dioxide) is removed and then only the amount of oxygen that was actually metabolized by the diver’s body is replaced in the gas so it can be breathed again.

Why dive a Closed Circuit Rebreather ?


 

An open circuit diver is often unaware of their invasive relationship to the underwater world.  The noise produced from exhaust bubbles and open circuit mechanics is frightening to underwater creatures. This noise may alter behavior patterns or drive animals away entirely.  By nearly eliminating the production of noise, rebreather divers are able to blend into the environment. The previously missed sights and sounds are amazing.

 

One of the considerations in cave and wreck diving is the effect of “percolation.” As bubbles hit an overhead environment, they may dislodge material, small and large alike. By reducing or eliminating bubble production, this risk is also minimized.
Most of the oxygen consumed in an open circuit system is never utilized. It is wasted in the form of bubbles. Recycling the breathing gas and scrubbing out the CO2 can dramatically increase dive time. With an 80 cubic foot tank, an open circuit dive to 100 feet will last between 15 and 30 minutes. The same dive on a closed circuit rebreather could last for several hours.
In effect, closed circuit rebreathers are like self-contained nitrox mixing stations. The best possible nitrox mix is being maintained throughout the dive. The on-gasing of nitrogen is minimized. The elevated level of oxygen will result in less fatigue following a dive.
The gas breathed from a scuba tank tends to be cold and dry; this is not the case for rebreathers. The gas breathed by a rebreather diver is warm and moist.
One of the drawbacks to open circuit scuba is the bulky nature of the tanks; they tend to be heavy and awkward. It is not uncommon to need between four and eight tanks for a weekend of diving. Transporting this volume of gear can really be a lot of work. A closed circuit rebreather could handle the same duration of diving with only two small tanks (approximately 19 cubic feet each).
 
 


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