We recently spent a week diving with a rEvo rebreather in the Amed area of Bali. For those who don’t know what a rebreather is, it’s basically a bubbleless version of scuba that allows the user to “rebreath” their exhaled air after it has been filtered. This is a much different experience than normal “open circuit” scuba and it’s a lot of fun!
Why Dive A Rebreather?
Of course this is a question many people ask. A rebreather has several advantages over open circuit but also has a variety of drawbacks as well. Let’s start with the advantages 🙂 Instead of exhaling our used air into the water column like a regular scuba unit does, a rebreather creates a loop system that constantly recycles our air. Using a soda sorb to clean the carbon dioxide from our exhalations, the system allows us to reuse the same air for a long period of time. We attach small oxygen and diluent tanks to the unit in order to add new gas into the loop when needed. No more full sized tanks are needed! The greatest benefit of this setup is that it allows the user to stay down for a very long time without running out of air. It’s possible to dive three or four hours on two 3 litre tanks of gas. The key is dialing in your oxygen mix to decrease nitrogen intake, especially on the ascent.
The disadvantages are also something to think about. A system with 100% oxygen installed can lead to big trouble if there is a malfunction. This could lead to either too much or too little oxygen which both can lead to an accident. Of course there is also the extra cost of a rebreather and the soda sorb needed to operate it. And the most annoying part, the time it takes to setup as well as clean!
The Fun Part
Once you have past all of the checks and head into the water, diving on a rebreather can be a lot of fun. One of the most interesting is the lack of bubbles in your face and in your hearing. The quietness of diving is a welcoming novelty. Although different technology is needed for monitoring gases, this is accomplished by modern computers made for the units. One of the most interesting things about diving with a rebreather is the differences needed for buoyancy control. It’s no longer about controlling the lung volume as most “air” is held in the loop. Therefore, experienced open circuit divers do have to get used to a new style of buoyancy control.
We will be diving more with rebreathers in the future. The bottom time allowed by this technology is definitely an advantage when it comes to filming underwater. No longer are we limited to the amount of gas in our cylinder and can dive for 3 or 4 hours at a time. Although doing that would certainly make one a very hungry diver!