8 hydrographic survey
says the vehicle will be ideal for large nautical charting
surveys and mine defence work.
The USS is designed to operate just below the water’s
surface with a mast extending above the waterline.
Payload sensors include a keel-mounted side scan
sonar, multibeam echosounder, and CTD (conductivity,
temperature, and depth). The mast includes a video
camera, C-Nav DGPS, and wireless antenna for high-
speed telemetry of data.
According to the company’s CEO Thomas Chance, like
an AUV, the vehicle will be able to operate autonomously
in a wide range of sea conditions, yet with the exposed
mast, data can be reliably positioned with DGPS and
relayed back in real time.
C&C Technologies operates worldwide and provides
a broad range of offshore survey services, C-Nav global
DGPS services, and claims to be the world leader in
deepwater AUV operations. However, it was not C&C
Technologies vehicles that Scottish firm NCS Survey
Fig. 2. Nereus, poised for its record breaking deep dive.
ordered. Instead the firm went for a pair of Gavia AUVs
➠
utilised for hydrographic and seismic survey operations. – one 500m-rated system and one 1000m rated system.
The tethering system for Nereus presented one of the These systems are specifically aimed at the shallow water
greatest challenges as conventional market and are understood to be
steel-reinforced umbilicals would the first Gavia AUVs to enter the
be too heavy and, according to oil and gas market as a service
WHOI, break under its own weight. provided by a survey contractor –
To solve this challenge, the but general survey, not seismic.
Nereus team adapted fiber-optic As a response to NCS Survey’s
technology developed by the US decision to select Hafmynd, the
Navy’s Space and Naval Warfare Icelandic manufacturer of these
Systems Center Pacific (SSC Pacific) vehicles has created a new line
to carry real-time video and other named the Gavia Offshore Surveyor.
data between the Nereus and the Delivery is expected in late
surface crew. September this year but NCS
Similar in diameter to a human Survey have already secured a
hair and with a breaking strength contract, which started in May and
of only 4kg, the tether is composed will use the demonstration system
of glass fibre core with a very thin from Hafmynd for this project.
protective jacket of plastic. The Offshore Surveyor has
Nereus carries some 40km of numerous improvements and
this cable in two canisters the size upgrades from the standard Gavia
of large coffee cans that spool vehicles that enhance the operation
out the fibre as needed. By using and usability for commercial
this very slender tether instead applications. Both NCS Survey
of a large cable, the team was
Fig. 3. C&C Technologies is, at the time
systems will have a payload of a
able to decrease the size, weight,
of writing preparing to sea trial its
multi-beam echo sounder (MBES),
complexity, and cost of the vehicle.
unmanned semi-submersible in the
sidescan sonar, digital camera,
NCS Survey has chosen GAPS,
Gulf of Mexico.
doppler velocity log (DVL), Kearfott
IXSEA’s Global Acoustic Positioning T24 IMU, DGPS and sound velocity
System, for the acoustic positioning of a number of meter. In addition, each system will be fitted with a
subsea structures for a North Sea renewables project due Seebyte SeeTrack module to allow the tracking of linear
to start this month. features such as pipelines and trenches.
Staying in the US, C&C Technologies of Lafayette was The sounder is a Geoswathe Plus 500kHz machine
at the time of writing, preparing to perform sea trial its capable of a survey swathe width of up to 190m.
unmanned semi-submersible (USS) in the Gulf of Mexico. There are various SSS options for the vehicle but NCS
The vehicle was designed and built over the last Survey have opted for the unit that has been proved
three years as a substitute for the standard hydrographic with the Seebyte module, a Marine Sonic Technology
survey launch. Powered by a 30bhp diesel engine, C&C 900/1800kHz system. l
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