Sonar Systems Help Search Teams, Scientists and Salvors

Domenti Apakidze on the Black Sea with his JW Fishers side scan sonar (Photo: JW Fishers)

Posted by Eric Haun

A variety of sonar systems are now being used by law enforcement
and public safety dive teams, universities and salvage companies
for recovery operations, subsea surveys and marine research.
Sonars produce almost photographic images of the underwater
environment regardless of water clarity. Side scan sonar can
sweep several hundred feet of ocean, lake, or river bottom in one
pass of the boat allowing large areas to be searched or surveyed
quickly. Scanning sonar, which operates in water similar to the
way radar operates in air, can image a 200 foot circle on the
bottom in less than a minute. Sub bottom profilers transmit a
sound wave that penetrates soft bottom and reflects off the
harder substrate below showing what lies buried in the bottom.
These sonar systems help save time and money, increase diver
safety and allow more extensive study of the marine environment.

China's Yangtze River, known locally as the Chang Jiang, is the
country's longest river and the third longest in the world. It
originates in the mountains of the Qinghai Province and runs from
west to east, terminating in Shanghai where is pours into the
East China Sea.

It is an economically important route for ships carrying freight
from inland regions to the coast. The waters of the Yangtze are
notoriously difficult to navigate with unseen submerged
obstructions, treacherous crosscurrents and whirlpools. Many
ships have been sunk and many others have lost precious cargo
after being tossed about in the raging river. It is not unusual
for large containers to be thrown overboard where they are
quickly engulfed in the river's muddy bottom. With new
improvements in underwater imaging technology, a concerted effort
is now being launched to locate the many containers littering the
bottom of the Yangtze. One of the tools being employed in these
salvage operations is JW Fishers SBP-1 sub bottom profiler. This
low frequency sonar system can easily locate these cargo
containers buried in the soft bottom.

Chong Zhao is an assistant professor at Dalian Ocean University's
Key Laboratory of Mari Culture and Stock Enhancement. His
research includes work on how changes in the ocean environment
affect marine life in the East China Sea. This area is an
important food source for the Chinese people. Two of the tools
Zhao and his team use to gather data are JW Fishers SSS-100K/600K
side scan sonar and the SeaLion-2 ROV. The side scan provides
high resolution images of the sea floor allowing scientists to
clearly see the varying bottom conditions in different areas. The
remote controlled underwater camera system then allows
researchers to view and document the variety of marine life that
inhabit these unique benthic environments.

Williamson Marine Service has been doing commercial diving and
underwater engineering work in Hong Kong since its founding in
1968. The company utilizes an extensive list of high tech
equipment in its operations. Video systems are used for
inspections of underwater structures and ships. Sonar systems
help locate shipwrecks, survey archaeological sites, find lost
anchors and propellers, examine pipelines and sewer outfalls and
much more. Williamson recently acquired a JW Fishers SCAN-650
scanning sonar which can serve a variety of functions. Mounting
it on an ROV aids in navigating the vehicle to underwater sites
beyond the visual range of the onboard camera. The sonar can be
deployed from a boat letting its sonar beam sweep a wide arc
around the boat showing the topside operator what lies on the
bottom. It can even be affixed to a diver's helmet providing
topside personnel a clear picture in a low visibility
environment, letting them guide the diver directly to the job
site.

When two recreational scuba divers went missing off Gonio, a
coastal town on the Black Sea, Domenti Apakidze was working on a
research project with the State Hydrographic Service in the
Republic of Georgia. Domenti and his team offered to assist in
the search using their JW Fishers SSS-100K/600K side scan. This
sonar is a tool commonly used in hydrographic surveys. It creates
a detailed map of the underwater terrain and any obstructions on
the bottom that could pose a hazard to navigation. The side scan
is also routinely used by law enforcement agencies and public
safety dive teams to find sunken vessels, submerged vehicles and
drowning victims.

Mar 8, 2017

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