O
ver the last 50 years, polar diving has yielded a
wealth of scientific information and proven to
be an indispensible sampling and observational
technique. Despite technological advances,
exclusively mechanical or remote methods cannot replace
divers in the water under the ice. Ice diving is both politically
and scientifically interesting and has received international
research funding in the fields of medicine, physiology,
fisheries and ecology. Basic climate-change research focuses
on polar regions because of their global importance.
Preparation
Dedicated ice-diving equipment and specialized training
of divers, dive supervisors and medical personnel must
feature prominently in the operational logistics of ice diving.
Traditional models of dive planning do not transfer well
to extreme-environment diving; the margins of error are
much narrower. Treating ice-diving operations as remote-
environment activities and taking extra steps to prepare for
managing decompression illness increase the probability of
successful diving missions. Gas-management and emergency-
response planning in extreme-environment diving require
special consideration — not unlike that required in cave,
rebreather or wreck diving.
Diving under polar ice is an obvious example of extreme-
environment diving because of the many physiological,
equipment-related and training parameters that affect divers.
Regulator performance and thermal protection are two
principal concerns. In polar regions there is a chance that
first- or second-stage scuba regulators will malfunction due to
the accumulation of ice in or around the regulator, resulting
in complete occlusion of air flow or a massive free-flow
that could rapidly expend a diver’s air supply. Factors that
influence the likelihood of regulator freeze-up are design and
configuration (determined by the manufacturer), quality control
(
unique to the individual regulator), depth (due to increased
gas density), mass flow (a product of depth and respiratory
volume), water intrusion, time and temperature. Most free-flow
problems occur in second stages, which means careful predive
management is essential. Regulators must be kept warm and
absolutely devoid of any residual fresh water. Not breathing
from the second stage prior to immersion prevents moisture
from a diver’s breath from crystallizing on the low-pressure seat,
which is a trigger for further ice accumulation and free-flow.
Minimum ice-diving qualification criteria that have proven
effective in scientific diving include at least a year as a certified
diver, 50 logged open-water dives, 15 logged drysuit dives
and 10 logged drysuit dives in the preceding six months.
Unpacking a new drysuit for the first time on a liveaboard
vessel is not considered good preparation; ice divers must
become proficient with the gear and techniques that will be
used prior to their deployment on ice-diving expeditions.
Equipment
Divers should be equipped with two fully independent
regulators attached to an adequate gas supply whenever they
dive under a ceiling. Proper use and pre- and postdive care
substantially improve the reliability of regulators. A large
volume of air exhausted rapidly through a regulator will almost
certainly cause a free-flow. Drysuit inflator hoses are also subject
to free-flows and are attached to backup regulators in case the
air supply to the primary regulator must be turned off to stem
the loss of air. When inflating a drysuit or a BCD, use frequent
short bursts of air. The primary cause of regulator free-flow is
entry of water into the mechanism and the water freezing once
the regulator is used. Fresh water in a regulator from rinsing or
melting snow may freeze as soon as the regulator is submerged
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FALL 2012
RESEARCH, EDUCATION & MEDICINE
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A D V A N C E D D I V I N G
Ice Diving
The push to the poles
B y M i c h a e l A . L a n g , D . P H I L .
Courtesy Michael Lang