Sidemount has been around since the 1960s. It originated in the UK with sump divers. In the 70s it was adapted for the Florida caves, mainly in systems with small passages. The popularity of sidemount did not emerge until recently. More and more equipment manufactures and training organizations have embraced sidemount. The question is, “What is sidemount and why do it?”
Sidemount is a configuration which has tank is mounted alongside the diver, not on the back of the diver, a benefit while diving in a confined space such as a wreck penetration.
Sidemount use is growing with technical divers and is becoming more popular with recreational divers.
The benefits are:
Single tanks are often easier to find and to transports. When diving in remote locations, the transportation is considerably less work. Sidemount equipment is also considerably lighter, and less bulky than back-mount rigs. A diver can also use whatever size tank is available. Duel 40s are great for recreational diving.
Sidemount diver has direct access to, and observation of, the regulators and tank valves of their cylinders. This allows for instant problem solving without ‘behind the head’ shut-down drills that require a higher level of mobility, flexibility and freedom to operate.
As stated sidemount places the cylinders under the diver’s armpits, in line with their body. This decreases resistance (improving air consumption and reducing fatigue)and lets the diver pass through smaller restrictions, if needed. Removing tanks and putting them in front, allows the diver to pass through very small passages and holes when performing a penetration dive, and it is just fun to do.
Direct access to life-support equipment (regulators, first-stages and valves) improves efficiency and speed of valve shut-down procedures, allows immediate identification of problems and provides the diver with quick access to safety procedures; such as regulator swapping (between cylinders), valve-‘feathering’ to access gas within a cylinder whose regulator has malfunctioned or even breathing directly from a tank valve, if you are having a really bad day.
Having the tanks next to the diver’s body, and beneath the armpits, serves to protect valves and regulator first-stages from collision, impact and abrasion damage, or accidental shut-down. It also significantly reduces the risk of entanglement behind the diver.
Sidemount offers greater stability, trim and control in the water. It is also less physically demanding to carry, and get into. The ability to attach, remove and replace cylinders while in the water allows the diver to avoid carry heavy back-mounted doubles. As well as reduced physical exertion when conducting regulator shut-down procedures, which is a major benefit to divers who suffer from shoulder or back injuries that reduces mobility.
Increased gas supply allows for longer dives and gas redundancy. Using nitrox and a nitrox computer allows for more no stop diving. Diver also carry their own back up air supply. Independent tanks provide true gas redundancy.
Side Note: Monkey diving is the term used to describe the use of a sidemount rig, using a single cylinder. It takes a little getting used to but easy to do.I prefer it when not teaching.