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Marine Electronics


October 2013 Issue

Coastline Surveys to Conduct Offshore Wind Farm Survey
Coastline Surveys Ltd. (Falmouth, England) has been awarded a contract to undertake offshore geophysical surveys for East Anglia Offshore Wind Ltd. (EAOW) in support of the development of the Offshore Cable Corridor for East Anglia Three and East Anglia Four.

EAOW is a joint venture between ScottishPower Renewables (Glasgow, Scotland) and Vattenfall AB (Stockholm, Sweden).

Together, they have been awarded rights to develop up to 7,200 megawatts of wind capacity off the coast of East Anglia as part of The Crown Estate's Round Three offshore wind program.

Coastline Surveys will undertake a series of bathymetric and side scan sonar surveys, sub-bottom profiling and high-resolution multibeam echosounder surveys. These will provide detailed information to support the environmental impact assessment and enable preliminary cable installation design to be undertaken on the additional area that is to be included in the Offshore Cable Corridor for East Anglia Three and East Anglia Four.

Coastline will deploy its survey vessel MV FlatHolm, which is fully equipped with a complete suite of survey equipment, along with its specialist team of hydrographic surveyors.

Saturation Divers Progress With SRP Repairs
Construction workers from Salt River Project (SRP), one of Arizona's largest utilities, and Seattle, Washington-based Global Diving & Salvage Inc. are in the final stages of a saturation diving project. Crews have completed the major project at Unit Four and were expected to then finish work on the intake structures for Units One to Three. The diving solution was chosen in order to avoid draining the reservoir level by 170 feet.

The project was prompted by a June 2012 collapse of a guide vane inside the penstock intake, the huge pipe that passes through the dam from Apache Lake into the generating unit below on the Canyon Lake side. The dam itself was unharmed and other structures remained sound. The result of the damage was the shutdown of Unit Four and the 119 megawatts of electricity produced by the pump-back unit.

Global Diving & Salvage early this year set up a huge working barge on Apache Lake next to the dam. Global Diving hauled 29 tractor trailer loads, which included the barge system supporting construction efforts, boats and other support features. Its 20-to-24-member crew working around the clock on the barge supported the divers working underwater.

At the project peak, Global Diving utilized two teams of two divers working around the clock. Global Diving's crew used saturation diving, where the divers breathe a blend of oxygen and helium and stay under pressure for up to 30 days. This allows the divers to work at depth for much greater periods than conventional diving allows.

While one diver remained in the diving bell, the vessel that brought the divers from the work area 160 feet below the surface of Apache Lake to the pressured habitat vessel on the barge, the other worked a five-hour shift. Roles were then reversed for the other five hours. Ten hours later, the second two-man crew repeated the process.

The new vanes fabricated and assembled by SRP are carbon-steel forms coated with corrosion protection that are filled by underwater concrete. Global Diving's tasks on the project included anchoring and securing the steel forms.

Falkor Explores Mid-Cayman Rise Using Nereus Hybrid ROV
In June, a team of oceanographers and astrobiologists on board the Schmidt Ocean Institute research vessel, RV Falkor, set sail on the two-leg Oases 2013 cruise to explore the Mid-Cayman Rise, which reaches to more than 6,500 meters depth.

Using the Nereus, a Woods Hole Oceanographic Institution (WHOI) hybrid ROV, scientists searched for life and geochemical phenomenon. Building on previous work in the region, scientists used Nereus to prospect for new hydrothermal vent sites. They also sought to extend understanding of the limits to which life can exist and of how geologic processes might generate the prebiotic materials believed to have been an essential precursor to life on Earth, and to help prepare for future efforts to explore for life on other planets.

The MacArtney Group's (Esbjerg, Denmark) A-frame was used to successfully launch and recover the Nereus. Using the A-frame and a MacArtney fiber-optical ROV winch system from the University-National Oceanographic Laboratory System East Coast Winch Pool, the Nereus was effectively deployed on multiple dives during the cruise.

Statoil, ABB to Develop Subsea Electrical Power Solutions
Statoil (Stavanger, Norway) and ABB (Zurich, Switzerland) have entered an agreement to develop solutions for subsea electrical power transmission, distribution and power conversion systems for water depths down to 3,000 meters and over long distances.

The agreement is in the form of a cost-shared joint industrial program (JIP) led by Statoil on behalf of other participating oil companies, with ABB as the technology developer. The agreement follows a large subsea electrification study executed jointly by Statoil and ABB during 2012. The JIP will develop technologies needed to provide electrical power to subsea pumps, electrical submersible pumps and subsea gas compressors for projects on the Norwegian Continental Shelf, in the Gulf of Mexico and other places around the world.

Subsea pumping and gas compression contribute to improved utilization of the oil and gas resources through higher recovery rates and reduced production costs, as well as enabling deepwater production.

Subsea electrical power distribution enables supply of all electrical loads using one single power cable. This greatly reduces the investment cost of the electrical system compared to existing solutions, which require one dedicated cable for each pump or compressor.

The technology will also enable the transmission of electrical power over long distances. This is important for the development of remote fields located far from infrastructure, including Arctic areas.

The total cost for the program, which has a duration of five years, is $100 million, including ABB funding.


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