Feature Article
ARUN KUMAR & N. BABU RAO
The submarine is a
deadly danger lurking
underwater for enemy
ships. But it could be
equally lethal for the
crew manning it. The
Defence
Bioengineering &
Electromedical
Laboratory (DEBEL)
based in Bangalore
has come up with an
indigenous Submarine
Escape Set that has
come up to the
expectations of the
Indian Navy.
A
submariner once remarked
– “What goes up, always
comes down, but what goes
down may not always come
up.” Obviously he was referring to the
submarine, which has its operational
abode under water. His apprehensions
are quite understandable considering
the lethal and hazardous nature of
underwater environment.
Life
protection and life support systems
become the primary concerns for safety
of personnel engaged in underwater
operations.
The submarine is a hydroplane
with
tremendous
operational
capabilities under water and is
fundamentally designed to serve the
needs of defence personnel although it
is also used for civilian purposes like
research, underwater exploration, oil
and gas platform inspection and
pipeline surveys and tourism.
The concept of submarine
development surfaced in the late
nineteenth century and was probably
influenced by the famous science fiction
novel 20,000 leagues under the Sea
published by Jules Verne in 1870. The
novel tells about the adventures of Prof
Pierre Aronnax and his friends aboard
the Nautalis, an electrically powered
submarine built by Captain Nemo.
Interestingly, some of the author’s
ideas in the book became a reality with
the development of high speed nuclear
and diesel submarines, which are
currently being used for secret
underwater operations. The author
also seemed to have a faint idea of the
military use of submarines and the
danger they pose to warships, as was
evident from the crippling damage
inflicted on British ships by the
German U-Boats in the two World
Wars.
Present day submarines are
capable of diving down to a depth of
250 meters or more, stealthily existing
under water for effective military
operations. Irrespective of the depth it
reaches, the submarine is so designed
that it always maintains the normal
atmospheric pressure of 760 mm of
mercury at sea level inside the
submarine. The total number of crew
inside the submarine generally varies
from two or three in a research
submarine to several hundreds in a
military attack submarine.
In the event of an accident or
incapacitation, the submarine crew is
forced to abandon the submarine and
reach the surface for safety. Otherwise,
they will perish, as it happened some
SCIENCE REPORTER, February 2010
45
Feature Article
Table-1: Signs and symptoms of decompression sickness (DCS)
DCS Type
Bubble Location
Signs & Symptoms
(Clinical Manifestations)
BENDS
Mostly large joints of
the body (elbows,
shoulders, hip, wrists,
knees, ankles)
· Localized deep pain, ranging from
mild (a “tingle”) to excruciating. Sometimes
a dull ache, but rarely a sharp pain.
· Active and passive motion of the joint aggravates
the pain.
· The pain may be reduced by bending the joint to
find a more comfortable position
· If caused by altitude, pain can occur immediately
or up to many hours later.
SKIN BENDS
Skin
· Itching usually around the ears, face, neck, arms
and upper torso
· Sensation of tiny insects crawling over the skin
(formication)
· Mottled or marbled skin usually around the
shoulders, upper chest and abdomen, with itching
· Swelling of the skin, accompanied by tiny scar-like
skin depressions (pitting edema)
NEUROLOGICAL Brain
CHOKES
· Confusion or memory loss
· Headache
· Spots in visual field (scotoma), tunnel vision,
double vision (diplopia), or blurred vision
· Unexplained extreme fatigue or behavior
changes
· Seizures, dizziness, vertigo, nausea, vomiting
and unconsciousness may occur, mainly due to
labyrinthitis
Spinal Cord
· Abnormal sensations such as burning, stinging,
and tingling around the lower chest and back
· Symptoms may spread from the feet up and may
be accompanied by ascending weakness or
paralysis
· Girdling abdominal or chest pain
Peripheral Nerves
· Urinary incontinence and fecal incontinence
· Abnormal sensations, such as numbness,
burning, stinging and tingling (paresthesia)
· Muscle weakness or twitching
Lungs
· Burning deep chest pain (under the sternum)
· Pain is aggravated by breathing
· Shortness of breath (dyspnea)
· Dry constant cough
The submarine is a
hydroplane with tremendous
operational capabilities
under water serve the needs
of defence personnel
although it is also used for
civilian purposes like
research, underwater
exploration, oil etc.
46
SCIENCE REPORTER, February 2010
time back in the case of the Russian
submarine, Kursk in August 2000.
The crew has to be provided with
life support systems to guard them
against environmental hazards such as
cold, reptile attacks, etc as well as from
the crippling effects of high pressure
on the human body. Besides, they
should also be provided with the
correct composition of gas mixtures i.e.
Nitrogen, Oxygen and Helium gases
at suitable pressure to enable them to
continue breathing during ascent.
Underwater Physiology
Any descent into the sea is known to
increase the pressure around the
human body alignments significantly.
In the case of personnel descending into
water, it becomes necessary to supply
air under pressure to prevent the
exposure of blood in the lungs to
sudden high alveolar gas pressures in
order to keep the lungs from
collapsing.
Normally, nitrogen,
oxygen and carbon dioxide are the
three gases to which a sea diver is
exposed, although helium can also be
used sometimes as a substitute for
nitrogen in the breathing mixture.
Nitrogen, which approximately
constitutes four-fifth of the air and
which at sea level pressure is not
observed to cause any adverse effect
on the body physiology, can be
expected to produce varying degrees
of narcosis at pressures existing beyond
50 meters depth. Sometimes the diver
becomes ineffective as a result of
nitrogen narcosis. To overcome these
environmental hazards, the diving
underwater
personnel
need
underwater breathing apparatus.
During ascent, the diver faces yet
another problem in which gases in the
breathing bag expand because of
reduction in surrounding pressure
leading to increase in buoyancy, thereby
causing rapid and uncontrolled ascent to
the surface. This leads to decompression
sickness (DCS). DCS results from gas
coming out of solution in the body fluids
and tissues when a diver ascends too
quickly. DCS is sometimes classified
according to symptoms as type I or Type
II with the latter characterized by more
severe neurological effects. Bubbles can
form anywhere in the body, but
symptomatic sensation is most
frequently observed in the shoulders,
elbows, knees, and ankles.
Report
Feature Article
Submarine
Skin Bends in
Decompression
sickness (left)
Table 1 gives symptoms for
different types of DCS. The “bends”
(joint pain) account for about 60 to 70%
of all altitude DCS cases, with the
shoulder being the most common site.
These types are classified medically as
DCS I. Neurological symptoms are
present in 10 to 15% of all DCS cases
with headache and visual disturbances
being the most common. DCS cases
with Neurological symptoms are
generally classified as DCS II. The
“chokes” are rare and occur in less than
2% of all DCS cases.
Skin
manifestations are present in about 10
to 15% of all DCS cases.
The large difference between the
ambient pressure and that of the
human body’s air containing cavities
may cause injury by damaging the
tissues involved. This injury is called
barotrauma. The different types of
barotraumas that commonly occur are:
Aural barotraumas (damage to the
eardrum), Pulmonary Barotramuma
(pressure damage to the lungs), Sinus
Barotrauma (painful inflammation of
the membrane of paranasal sinus
cavities), and Pneumothorax (lung over
expansion injury causing lung
collapse).
Escape Mechanisms
With the advent of underwater
technologies underwater operations
are becoming increasingly pertinent.
A lot of underwater strategic missions
are conducted by various Naval
services across the globe. So, in case of
any accident, rescue and life support of
personnel involved in underwater
operations assumes great significance.
As these devices are critical to save the
lives of users, a lot of prudence has to
be exercised in designing the
equipment.
Rescue from sunken/abandoned
submarines is a very difficult and
complicated process. The mortality
rate depends on the nature of
wreckage and availability of facilities
and the time lapsed. Globally,
submarine escape is a highly
Escape hatch
Access
hatch
Torpedo
room
Torpedo
Schematic Diagram
of a Submarine
Escape Hatch (inset)
complicated
operation for
which rigorous
indoctrination
is required for
the sailor. All
the escape drills
have to be
f o l l o w e d
meticulously.
Various
countries all
over the world
have attempted
and perfected
systems to meet
this
goal.
Different
countries use
d i f f e r e n t
methods
of
rescue such as:
A
F
D
G
C
E
B
A: Rescue Ship; B: Sunken Submarine; C: deep Submeragence Rescue Vehicle (DSRV); D: McCann
Bell; E: Remote Operated Vehicle (ROV); F: REMORA; G: Free ascent escape by submarine escape set.
Submarine Rescue Chamber
(McCann Bell) (Turkey, USA, Italy);
DSRV (Deep Submergence Rescue
Vehicle) (USA, Russia);
LR5 (UK),
ASRV (Australian Submergence
Rescue Vehicle) (USA, Russia);
REMORA (Australia);
URF (Sweden);
SRV 300 (Submergence Rescue
Vehicle) (Italy).
These rescue vehicles get attached
to the escape hatch of the submarine
during rescue operations. However,
the Submarine Escape Set (SES) is for
individual escape. This is the only set
that allows unaided safe escape.
Submarine escape systems are a
technology by themselves, which very
As these devices are critical to save the lives
of users, a lot of prudence has to be exercised
in designing the equipment.
few countries have perfected.
Depending upon the situation in the
sunken submarine, individuals can don
the SES and escape through either the
escape hatch or conning tower or
torpedo tubes of the submarine.
Indigenous Submarine Escape
Set
Presently, a fleet of 16 submarines is
under operation with the Indian Navy
and the crew is entirely dependent on
Escape Sets (ISP-6)) imported from
Russia. With 20 more submarines
likely to be inducted in the near future
SCIENCE REPORTER, February 2010
47
Feature Article
MacCann Rescue
Chamber
Tower in Submarine
Hydro suit
Breathing
Apparatus
Test Facility
Submarine
Escape Set
along with the indigenously developed
Advanced Technology Vessel (ATV)
and the Akula class Russian nuclear
attack submarine the demand for SES
is bound to increase.
The development of Submarine
Escape Set involves technologies from
several areas like Mechanical
Engineering, Chemical Engineering,
Textile Engineering (Coated and Heavy
textiles), Polymer Science and
underwater Physiology.
Since DEBEL belongs to the Life
Sciences Cluster of DRDO and is a
multi-disciplinary
Laboratory
having considerable knowledge and
expertise in all the above areas and
since it also has the capability for
development of Life Support Systems
it has undertaken the task of
indigenously developing suitable
SES for use in Indian Navy.
The SES consists of a hydro suit
and a breathing apparatus. The hydro
suit is a full coverage rubberized suit
to protect the wearer from the
parasitical effects of hypothermia and
reptile bites. It is made up of air and
watertight costume of neoprene coated
nylon fabric. The hydro suit has been
designed in two sizes: medium (upto a
height of 198 cm) and large (in the
height range of 199-216 cm). The boots
are of size 43. The hydro suit maintains
its air/watertight integrity when the
pressure in the main body is 350 + 10
mm wc. The buoyancy compartments
maintain their airtight integrity when
inflated to 450 + mm wc.
48
Submergance
Rescue Vehicle
The breathing apparatus caters to
the breathing needs of the wearer until
the wearer comes to the surface. This
is a self-contained close-circuit
breathing apparatus that allows the
submariners to pass through various
depths from 100 m to surface with stops
at intervals of 10 meters during buoy
rope ascent. This is a vital life saving
equipment that provides breathing
gases of varying compositions from
oxygen and mixture cylinders fitted
with reducers that work as per depth
requirements. A canister is provided
in the breathing circuit for removing
the carbon dioxide thus enhances the
set’s endurance.
The total weight of the SES does
not exceed 25 kg with the weight of the
hydro suit being 11 kg and that of
breathing apparatus being 14 kg.
The hydro suit as well as the
breathing apparatus were subjected to
trials at the laboratory and field level.
The functional evaluation of the
breathing apparatus components and
hydro suit were done under simulated
conditions at DEBEL. After this, the SES
was tested by sailors and officers at
Vishakhapatnam and Mumbai. After
successful completion of all the stages of
the tests, the equipment has been accepted
by the Navy. The item is expected to go
into production in the near future.
SCIENCE REPORTER, February 2010
It is very essential that the Hydro suit
and the Breathing apparatus, which are
critical life saving equipment are tested
before each use. The Hydro suit parts
like front and spinal buoyancy
compartments and the main body have
to be tested for water and airtight
integrity. Similarly the breathing
apparatus components such as oxygen
reducer flow, mixture gases flow
through automatic demand valve,
pressure release valve, valve chest and
regenerative canister are also required
to be tested for their functional
parameters.
Test facilities are not available
commercially and hence need to be
developed in-house. For this purpose
Testing Facilities
DEBEL has indigenously developed a
suitable test facility for functional
evaluation of their components. This
Test Facility, which is not only complex
but also unique, is the only test facility
available for carrying out all the critical
tests of the indigenous SES developed
by DEBEL. The Indian Navy has
procured this also.
Mr Arun Kumar and Mr N. Babu Rao are with the
Defence Bioengineering & Electromedical Laboratory
(DEBEL), Defence Research & Development
Organisation (DRDO), P.B. 9326, C.V. Raman
Nagar P.O., Bangalore-560093