What is Sidemount Diving?
So for the last few years I have been diving a sidemount configuration
in both wrecks and caves and I regularly get asked why? So I decided to
put together a small article on my reasons highlighting some of the benefits
it brings me over conventional back mounted gas supply. The article is
not intended to teach sidemount diving in full as training from an experienced
instructor and diving utilizing sidemount considers many variables one
might not if self taught.
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Traditionally British cavers used sidemount as a means
to dive sumps allowing further passage in dry cave systems. In recent
years divers all over the world have implemented sidemount diving as a
means to access dive sites that would be logistically challenging to enter
with heavy double manifold tanks as used by open circuit technical divers,
further more side mounted configurations allow divers to penetrate very
tight and challenging spaces as gear removal and monoverablility are just
some of the benefit sidemount diving allows.
Before I get into highlighting some of the benefits of
sidemounting and equipment configuration I feel its important to state
that divers choosing to use technical configurations must first plant
a firm knowledge base of dive theory and experiences, you know that old
saying “learn to walk before you can run” well that sings
true for those considering advanced level diving techniques.
Lets take a look at the basic sidemount configuration. Obviously
theirs more to it than just clipping on two bottles and going diving,
first of all we must consider streamlining the diver to produce a well
trimmed out balanced diver in the water this is achieved partly by the
placement of each stage tank. Tanks are normally clipped along the torso
using snaps fixed to a butt pad or hip mounted d-rings and then looped
in bungee around the cylinder neck to retract the tank under the diver
armpit to ensure a sung fit. Tank size and material need consideration
as steel vs. aluminium trim out differently and full tanks vs. empty tanks
may require adjustment during the dive, this is all achieved in observing
the tanks buoyancy characteristics on check out dives when full and near
empty.
At first glance a sidemount harness may look like a conventional
scuba system but in order to achieve good results a few changes are made,
there are several commercially available sidemount rigs currently on the
market most integrating a webbed harness system and wing all-in-one removing
the necessity of a solid backplate as this restricts the diver and has
a tendency to catch on things during a dive. The wing should be adjusted
to fit close to the diver to stop the effect of butterfly wings, most
of the wings create buoyancy around the divers hips, as this is where
it is needed to counter the weight of the sidemounted tanks. Some divers
may choose just to use drysuit buoyancy but this leaves little redundancy
if the suit was to fail during a dive.
The regulator set-ups are quite similar to those used
on decompression bottles in technical diving. One of the regulators is
normally fitted with a longer hose aiding the supply of gas to a diver
in an out of air emergency. Unlike diving back mounted doubles the divers
are now able to pass off the bottle allowing easier and faster exit in
the emergency. The other regulator is on a shorter hose and secured around
the divers neck in a bungeed necklace. Using this configuration requires
the diver to regularly switch regulators to maintain even tank buoyancy
as the gas is breathed this also ensure that both regs works, when the
diver is not breathing on the long hose it is secured to the right d-ring
using a small clip. Both regulators are fitted with pressure gauges normally
on short 6-inch hoses and low-pressure hoses to inflate the wing and drysuit
if required. I have found good regulators to be those that swivel similar
to the Apeks DS4 and mk25 scubapro as they aid good hose routing.
As it is normal that the sidemount diver uses this configuration
to dive caves and wrecks we should also point out the need and placement
of additional equipment, lights, accessory like cutting tools, spools,
reels, markers are better stowed on the rear of the dive to avoid anything
dangling free, the purpose built harness systems include rear positioned
rings for this, small attachment like arrows, cookies can be stowed in
a small pocket and clipped also to the rear. Many choose to use the standard
canister light but those diving in tight spaces may integrate lights to
a helmet this allows hands free operations and also protects the divers
head; lights are normally removable so the diver can access them if required.
Gas management is critical in all overhead environments
requiring careful planning and monitoring on all dives. Divers should
always know their personal gas requirements prior to a dive over distance
and plan for ample reserve. Using the sidemount configuration we must
switch regulators during the dive to stay balanced this also requires
the diver to consider reserve gas in a single tank in the event one of
the valves fails, access to all the gas is now possibly cut. Carrying
some small tools adjustable wrench, o-rings in your cargo pocket may allow
a diver to fix a problem in the water allowing access to the gas. If the
diver is executing deep/long technical dives requiring decompression gases
it is important that the dives follow a standard gas switch procedure
to avoid breathing the wrong gas at depth and risking toxicity issues.
Stress environmental problems all slow down an exit so this must be factored
in the reserve gasses.
So above we have briefly discussed some of the setup of a sidemounted
rig so it needs a mention that it’s not always the best configuration
for all types of diving. It does require a diver to invest time and money
to master this configuration. A diver having to remove tanks may become
unstable especially diving dry and using heavy steal tanks. Other than
that there really are not too many down sides. Other plus points include
ease of entry to the water, rescue maybe easier as its fast to remove
the tanks without taking of the full harness.
If you would like to try sidemount configuration or expand your diving
into overhead wrecks and caves please feel free to email Mathew at info@protechdivers.com
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