SIDEMOUNT DIVING

What Is Sidemount Diving?

Sidemount is a scuba diving equipment configuration which has diving cyclinder mounted alongside the diver, below the shoulders and along the hips, instead of on the back of the diver. It began as a configuration popular with advanced cave diving, as smaller sections of cave can be penetrated and tanks can be changed with greater ease. The same benefits for operating in confined spaces were also recognized by divers who conducted technical wreck diving penetrations.

Sidemount diving is now growing in popularity within the technical diving community for general decompression diving, and is becoming an increasingly popular specialty training for recreational diving. 

Terminology of Sidemount Diving:

Sidemount Diving

Sidemount diving is the, now increasingly formalized, approach towards conducting dives with 2 or more primary cylinders secured at the side of the body and in line with the torso – with no cylinders on the diver’s back. A common feature that defines sidemount configuration is the use of bungee cords to provide an upper attachment on the cylinder valve, normally routed from behind the diver’s upper back, whilst the lower cylinder is secured to the diver’s lower harness (butt-plate or waist D-rings) via bolt-snaps.

Sidemount Staging

Sidemount staging is the practice of using sidemount configuration (bungee loops and/or buttplate rails) as a means for stowing stage/deco cylinders in a streamlined manner against the sides of the torso, when otherwise diving in back-mounted doubles or CCR.

Stage-Only Diving 

Stage-only diving is the use of standard deco/stage cylinder configuration, without back-mounted cylinders, on an otherwise standard, or partially modified tec/rec BCD. The lower cylinder is attached to waist D-Rings and the upper cylinder to shoulder D-Rings, both via direct bolt-snap. Some divers (untrained in specific sidemount diving techniques) often incorrectly assume this approach to be sidemount diving. No bungee cord is utilised in the upper attachment, causing the cylinders to hang low beneath the diver and not in line (parallel) with their torso beneath their armpits. Without modification of the BCD design, the lack of back-mounted cylinders also causes taco’ing of wing designs and considerable instability.

Monkey Diving

Monkey diving is the use of sidemount configuration/procedures, whilst only carrying a single cylinder. It is presented as an option on some recreational level sidemount courses and may also be a considered strategy for certain overhead-environment (cave/wreck) penetrations. The use of a single cylinder may require a strategy of counter-weighting to prevent diver instability in the water, depending on the buoyancy of the chosen cylinder.

No-Mount Diving

No-mount diving is a specialized overhead-environment strategy for dealing with particularly tight restrictions. This may involve divers wearing a very basic harness under their existing configuration, or simply hand-carrying cylinders. Upon reaching a restriction through which they couldn’t otherwise pass, they will ‘strip down’ out of their primary gear, hand-hold or attach a cylinder/s to their ‘no-mount’ harness and move forwards. A ‘no-mount’ harness can consist of nothing more than a weight-belt with several D-rings attached. The evolution of sidemount techniques and configurations has largely made this approach unnecessary, as a minimalist sidemount harness/BCD can be worn beneath back-mounted doubles, or even a CCR.

Benefits For Sidemount Diving:

Flexibility

The sidemount diving approach offers divers significant benefits to the flexibility of their approach. Unlike back-mounted doubles, acquiring and transporting sidemount suitable cylinders is often much more convenient and accessible. Sidemount diving configuration allows the travelling diver to conduct technical and/or overhead environment dives without having to source traditional back-mounted cylinders. When diving in remote locations, the transportation of diving logistics, especially by hand, is considerably less physically taxing. Sidemount diving equipment is also considerably lighter, and less bulky than back-mounted alternatives – allowing for easier and cheaper (considering the rate of many airline’s excess baggage costs) travel.

Accessibility

Unlike back-mounted cylinders, the sidemount diver has immediate access to, and observation of, the regulators and tank valves of their cylinders. This enables immediate problem identification and allows swifter resolution, without recourse to ‘behind the head’ shut-down drills that require a higher level of mobility, flexibility and freedom to operate.

Streamlining

Sidemount diving configuration places the cylinders under the diver’s armpits, in line with their body. This decreases water resistance (improving air consumption and reducing fatigue) whilst also allowing the diver to pass through smaller restrictions than would otherwise be possible in back-mounted cylinders. The flexibility to remove tanks, and propel them in front, allows the diver to pass through very small passages and holes when penetration diving being limited only by the size of their bodies and exposure protection.

Safety

Increased accessibility to life-supporting regulators, first-stages and valves improves efficiency and speed of critical cylinder shut-down procedures, allows immediate gas-loss identification and provides the diver with quick access to alternative safety procedures; such as regulator swapping (between cylinders), valve-‘feathering’ to access gas within a cylinder whose regulator is malfunctioned/free-flowing or even breathing directly from a tank valve.

In addition, stowage of the cylinders next to the diver’s torso, and beneath his armpits, serves to protect vulnerable valves and regulator first-stages from collision, impact and abrasion damage, or accidental shut-down through contact with a ceiling. It also significantly reduces the risk of entanglement behind the diver, where it is least easy to rectify.

Comfort

Many divers will testify that sidemount diving configuration offers greater stability and easier-to-attain trim and control in the water. It is also less physically tiring to carry, and get into, sidemount equipment than with traditional back-mounted doubles – especially when operating from a small boat or a rough shore entry.

The ability to attach, remove and replace cylinders whilst in the water allows the diver to avoid ever having to carry heavy-weight back-mounted cylinders. This is combined with reduced physical exertion when conducting regulator shut-down procedures, which is a major benefit to technical divers who suffer from shoulder or back discomfort or reduced mobility from old injuries.

Redundancy of gas

Whilst technical divers have always utilized a redundant gas system, either isolated-manifold or independent back-mounted cylinders, recreational divers have traditionally resorted to using ‘pony cylinders’ or ‘ascent bottles’ as contingencies against out-of-air emergencies. Whether attached to the primary cylinder, or slung at the chest, these cylinders often presented problems with stability and streamlining, whilst simultaneously only providing a bare minimum supply of air for emergency ascent. Sidemount diving with two cylinders helps resolve stability and streamlining issues, and ensures that a truly capable redundant supply of air is maintained.

Technical divers debate the pros and cons of independent cylinders versus isolated-manifold doubles. Back-mounted manifold cylinders provide easy access to complete gas supplies, in the event of a regulator failure and shut-down. However, the manifold itself creates additional o-ring failure points and a failure in that component will deprive the technical diver of, at least, one-half of his remaining gas supply. Independent cylinders, when sidemounted, provide true gas redundancy, whilst offering access (via switching regulators between cylinders or feather breathing of all remaining gas.