BCDs
(Buoyancy Control Device)
Scuba BCDs are part of the scuba
kit which gives the scuba diver control
over buoyancy. A simple BCD is merely
an inflatable jacket or vest and
is nothing more than a fancy life
jacket and will commonly be used
by swimming instructors or lifeguards.
However, a scuba BCD is much more
than that! The scuba BCD is integrated
with a harness to strap the tank
on your back, pockets and straps
for your gauges and octopus, it is
an inflatable vest and backpack in
one; it is the wearable item to which
all of the other gear is secured.
Just like the divers who wear them,
scuba BCDs come in many different
styles. The most common BCD are the "Jacket" or "Vest" style,
which is worn like an inflatable
vest with buckles in the front. The
vest style is distinguished by the
way it wraps around your front, with
side panels containing inflatable
bladders. In this way, the vest resembles
a typical "life vest" used
by boaters. The tank straps onto
the back and there are extra straps
and pockets on either side to secure
other gear, like the regulator hose,
octopus (spare regulator), gauges
and other sundry items. Another style
of scuba BCD is the "Wing" style,
which is conspicuously missing the
side panels, and instead has conspicuous "balloons" either
extending from the sides or alongside
the tank support. These are intended
to balance the buoyancy in the back,
where the greatest weight is carried
(being the tanks), and to make it
easier to assume a face-down swimming
position in the water.
Scuba BCDs are rated for lift capacity;
the amount of weight they can keep
afloat. To test lift capacity, a
BCD is laid flat on the surface of
the water and weights are suspended
and added to the BCD until it sinks.
The lift capacity of a scuba BCD
is a factor you can consider when
choosing a BCD to buy or rent. Due
to size, body fat, muscle mass, bone
density and lung capacity some people
are naturally more buoyant than others.
The least buoyant people will be
large men with high muscle mass and
low body fat. A less buoyant person
(someone who you would call a "sinker")
will need a larger lift capacity
from their BCD.
But remember, a scuba BCD offers
variable buoyancy control. By inflating
or deflating your BCD, you can adjust
your buoyancy to suit your own body,
weight, depth, compression and density.
The only time a diver should be concerned
with lift capacity is if they are
a "sinker" or if they are
in the habit of carrying an extra
40 pounds of camera equipment on
their dive!
Just as importantly, a scuba BCD
should fit properly. On the surface
your BCD will fit like a jacket,
not too tightly under the arms and
snug across your belly. When you
strap on the scuba BCD it should
be a little tight, but not uncomfortable.
Women should choose a BCD designed
for a woman's body, which every manufacturer
produces in dozens of styles.
More expensive (and decadent) scuba
BCDs are those which come with an
integrated weight system; these are
weighted and ballasted to render
your weight belt unnecessary. Some
scuba systems are so integrated that
the BCD, weights and breathing system
are all in one pre-assembled piece.
Whatever style of scuba BCD you
choose make sure your BCD is a good
one. Here are some things to consider:
- Proper fit
- Lift capacity
- Good construction
- Reachable pressure release valves
- Comfortable, quick-release straps
- Quick adjustment
- Pockets with zip or Velcro closure
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