Research
has often progressed with the development of the technology to observe details
more minutely than ever before and so has surveying. However, when it comes to
oceans covering a vast portion of the earth’s surface, the mammoth scale says
it all- there is still a lot to know about them and so discover a lot about
ourselves from the enormous timescale of their existence on planet earth. You
might be familiar with the programs working towards making humans settle on mars,
but still underwater habitats, their study and the plethora of knowledge to be
gained from such endeavours might not have equal appreciation from you yet.
Trust me, the oceans are worth looking forward to.
Scientific
research expanded beyond geographical barriers and we needed a better look at
the vast outer space and of course, the oceans, a sizeable part of life on
earth still remain undiscovered today. The search for fossil fuel reserves,
everything other possible human necessity grew, and so the Ocean Research
Vessels came in to being. Depending upon need, the earliest ORV’s did
hydrographic surveys, assessments of fish stocks, primitive study of properties
of water at varying depths, deploying buoys, etc. before the advanced vessels of
today which can do a lot like these and more:
- Study of the marine flora and fauna: this is an area of extensive ongoing research,
especially with the discovery of new species every now and then.
- Study of the interactions with the atmosphere: this receives
a lot of attention today especially with the growing concern with climate, the
data from such research is invaluable. So, it goes without mention, the study
of pollution and adverse anthropogenic factors on marine life are imperative.
- Study of wave phenomena, sea states, and seismic research: these become
important, especially when setting up offshore structures for the extraction of
resources.
Oceans
are arguably the biggest reserves of moisture on earth and also store and
release energy more efficiently than land.
Now,
how does the mission shape the design? An ORV houses advanced scientific
equipment taking down observations, often having delicate sensors and
components. The components may be either heavy or lightweight. The ship should
be able to optimise between cruising time and working time as the latter is
crucial. Again when cruising, the marine environment within its radius and the
season of operation is important. The cranes and winches for lowering/deploying
the scientific devices and their loading conditions and strategic positioning
should be taken care of.
Here I
am trying to give you a standpoint to approach the problem with. When given the
task of designing an ORV, you should first fix the vessel parameters, generally
all ORVs require reasonably very good stability in the sea states of their operation which calls for an appreciable length/beam ratio. The sea states take into account the maximum
wave heights possibly encountered and so you would have decide the speed in
each sea state, given that your equipment which would be exposed on the deck
are not affected in a large way.
Speaking of deck area, ORVs have large exposed
deck spaces for container labs (if any), special frames called the A-frames and deep sea winches with their extensive cabling for lowering and
retrieving equipment. However the length of the ship puts constraints on the
equipment it can carry and the endurance (i.e. period of operation- the crew
and scientists aboard also matter) of the vessel. However a vessel of
intermediate size (around 100m) can house all the ones mentioned above. Then there are other factors
like having advanced manoeuvring capabilities and the ability to operate around
ice. Ocean Research Vessels often have Twin Screw Propulsion owing to its
enhanced manoeuvring capabilities.
ORVs
should also necessarily be ‘quiet’
ships. This means both external and internal noise should be minimum. External
noise components are reduced by proper fairing of the hull shape. This shape
when optimised to allow smooth flow around it ensures minimum external noise
and subsequently, hull vibrations are reduced. Another source of external noise
are the propellers and they subsequently need to be minimized.
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| Fig. 1:Innovations in hull design have been incorporated into the newer generation of ORVs like in this case, the Ulstein's X-Bow concept (Courtesy: www.arabianoilandgas.com ) |
Sources
of internal noise are reduced in many ways in these ships by the use of motors
instead of direct-drive diesel propulsion. Other methods are the use of Hull
Dampening and Bulkhead Insulation. We can discuss that another day.
It is observed that such ships have conventional 12
kHz, and 3.5 kHz echo sounding systems and provision for additional systems as
needed. Something worth considering here is the use of multi-beam echo sounder which
is a modern technology and an improvement over single beam and earlier lead
line techniques as it can provide a better area of coverage while covering a
fraction of the surveying length.
Most advanced ORVs
have Dynamic Positioning Systems (a standard on many vessels today) which develop
a numerical model of the ship and based on the response from waves, are able
control the rudder angles, propeller operation, bow thrusters in a combined
manner allowing the ship to hold its position or course automatically with high
accuracy. They require Global Positioning or some sort of position sensors, gyro compasses, etc. The vessels operating in Polar Regions have
extra-strengthening (ice-class vessels)
for the ice cover they are about to encounter. Sagar Nidhi is our very own
Indian ORV with both of the above features as we would see later.
Research
vessels necessarily require laboratory spaces and stores for scientific
equipment, these are exclusive to them only. Laboratory spaces cover a substantial
part of such designs. Laboratories have to be fabricated using uncontaminated
materials and a good design would allow maximum lab cleanliness among the
furnishing, cabling, hatches and fittings. Proper ventilation network with fume
hoods is essential. Laboratories on board are often broadly divided into wet
labs, dry labs and electronic labs if they are present separately from dry
labs. Access between laboratories are usually such they are convenient and at
the same time do not act as general passageways.
SCIENTIFIC EQUIPMENT
Some of
the equipment commonly used on such vessels are:
CTD
Normally on many ORVs. Used
for basic Conductivity, Temperature and Depth measurements. Used single or in
cluster arrangements called ‘rosettes’ and lowered into the water normally
using an A-Frame.
CORER
Collection of sediments from
the ocean floor. Information from the soil several layers deep helps in
understanding past history and also for climate changes, weathering phenomena.
WATER SAMPLING (NISKIN BOTTLES)
Other than the CTD apparatus
these equipment's are also used for detecting presence of biological life,
nutrient content and dissolved oxygen. Limited to small parts of the ocean area
and is time consuming.
BATHYMETRY DEVICES
Underwater analogue to
topography of sea bed. Use of side scan SONARs, single beam echo sounders,
these reveal the underwater morphology and geological history.
MULTI BEAM AND SINGLE BEAM
Use of acoustic waves at
certain frequency ranges which generate 2D and 3D representation of the data of
the ocean floor with depth. These are reasonably accurate.
SECCHI DISK
Measuring the transparency of
the water body. The scale is chosen as per depth at which the disk when lowered
into water using a rope ceases to be visible.
PLANKTON NETS
Collect planktonic organisms.
The size of plankton to be caught can be set by changing the size of the funnel
shaped net used aboard the ship for the purpose.
Some Champions
Here are a few ORVs which
have served towards knowing our oceans, the environment, and the planet as a whole.
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Fig. 2:ORV Sagar Nidhi
(Courtesy: www.tu.no ) |
ORV Sagar Nidhi
ORV Sagar Nidhi is owned and
operated by the National Institute of Ocean Technology, India. This vessel is
state of art with ice class capabilities. Accommodating 30 Scientists with a
crew of 24-25, this vessel can do a variety of Underwater and Oceanographic
Research procedures. Provided with Diesel Drive Propulsion and DP Systems. This
ship houses excellent navigation systems with an Integrated Bridge and can hold
live communication with the shore which will soon be enhanced by the
introduction of a VSAT within the system.
 |
Fig. 3:ORV Sagar Kanya
(Courtesy: www.ship-technology.com ) |
ORV Sagar Kanya
This vessel is owned and also
operated by the Indian National Centre for Antarctic and Ocean Research. This
vessel was delivered by Germany in 1983 to the Ministry of Earth Sciences,
India. This vessel conforms to the class requirements of Lloyds Register of
Shipping and the Indian Register of Shipping. Like ORV Sagar Nidhi, it is fully
automatic diesel electric with type twin screw propulsion and on board DP
systems. Both vessels have endurance of around 45 days continue to be
workhorses for the service of their organizations.
 |
Fig. 4:ORV Sagar Kanya
(Courtesy:www.abc.net.au)
|
Aurora Australis
Currently owned by the British
shipping and Logistics Company, P&O Maritime Services, this vessel is an
icebreaker built and launched in 1989 and in service since then. This vessel
was originally designed as a multi-purpose research ship. The crew on board the
vessel is 24 and this vessel can carry up to 116 passengers. Ship houses
laboratories for extensive oceanographic and meteorological research. The ship
can allow the operation of up to 3 helicopters from the helideck. The ship is
frequently used by the Australian Antarctic Division (AAD) and has been used
Department of Defence of the Royal Australian Navy among others mainly for
research and supply purposes.LSD
Article By: Sudripto Khasnabis
