My first courses were sidemount and technical sidemount. Sidemount diving, as the name suggests, involves placing your tank my hands and knuckles were covered in cuts by the end of the session. The idea is that you can unclip the tanks and put them out in front of you, Superman style, thus streamlining yourself. After some sizing adjustments to the harness, the afternoon dive went much more smoothly. I was now comfortably unclipping and ‘Superman-ing’ with the tanks. Compared to having doubles on your back, sidemount offers an incredible level of freedom. Matt set up obstacle courses and we were soon flying around them with tanks held out front, barrel-rolling and even swimming upside down.
Because single orifice duals and backmounted independencies are less common today, backmounted doubles became popular. Independents have two cylinders strapped to the back of one another with independent regulators. If the 1st stage failed, the diver would only need one cylinder. Single orifice twos were two cylinders that were connected with a regulator and a valve. A failure on the first stage would result in gas loss. Both problems are solved by the isolation manifold doubles that are used today. Each cylinder may be used independently. But, divers can also use the same regulator to breathe gas from both. These doubles are often held together by metal bands. If necessary, the valves can be connected to an isolation manifold. Backmounted doubles diving has a similar profile to regular single-cylinder dives. However, the profile is vertically identical.
