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.
