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March 2011 Issue

Researchers Study Benthic Life at Marine Renewable Energy Sites
The Marine Institute at Plymouth University and Peninsula Research Institute for Marine Renewable Energy recently completed a project to survey potential offshore renewable energy sites and monitor benthic organisms.

Bowtech Products Ltd. (Aberdeen, Scotland) supplied a Surveyor-HD video camera and LED-1600 lamps for the project and also designed and supplied the topside control system and umbilicals specifically to meet the project requirements.

The companies said methods using bottom-towed sledges, divers or remotely operated vehicles were inappropriate due to cost and practicality. It was necessary to develop a method that was cost-effective, relatively nondestructive and suitable for a range of habitats, as future sites proposed for marine renewable energy are located over a range of habitat types.

The researchers developed a survey method using a high-definition (HD) video camera, plus LED lights and laser scale markers, mounted on a flying array that maintains itself above the seabed, grounded by a length of chain. Samples are taken during slow-speed tows of the gear behind a boat. The HD video and randomly selected frame grabs are then analyzed to quantify species distribution.

“Our new survey method using a HD camera mounted on a towed flying array allows us to quantify the seabed and the associated flora and fauna in adverse wave and tidal conditions over heterogeneous habitats (sandy, pebbly flats to challenging boulder fields and rocky ledges),” Dr. Emma Sheehan, lead author of a publication on the survey, said. “In addition, it is also cost-effective and can easily be used to survey large offshore areas.”


NodalSeismic Completes Magens Bay Project
NodalSeismic (Signal Hill, California) recently completed a project in Magens Bay. Located on an 84-square-mile tract near Hallettsville, Texas, the project required a total of 38 days (including mobilization and demobilization) and a 24-person line crew.

The 5,800-channel operation used FairfieldNodal’s (Sugar Land, Texas) ZLand cableless system, which has no geophone strings or external batteries. The crew was able to deploy 254 receivers per square mile, at a rate of 700 per day.

In total, the project required 12 trucks, 14 four-wheelers and one 55-foot equipment trailer, allowing for a much smaller staging area, Nodal-Seismic said. By contrast, a typical cable crew would have needed at least four trailers, the company continued.


Dyneema Ultrastrong Fiber Used for Deep-Sea Recovery
A salvage operation on a shipwreck 3,200 meters below the surface of the South Atlantic has been successfully carried out thanks to the use of lightweight ropes made with Dyneema® ultrahigh-molecular-weight polyethylene fiber, DSM Dyneema B.V. (Urmond, Netherlands) announced in February.

Dyneema fiber is used by Hampiojan (Reykjavík, Iceland) to make Dynex Warp, a patent-pending winch line for deep-sea lifting and lowering as well as for towing fishing trawls. The Dynex Warp rope was used by Seabed AS (Ervik, Norway) over several months on the MV Seabed Worker in a salvage operation to retrieve cargo from a sunken ship.

Dyneema said the depth of the wreck meant that use of steel rope would have been virtually impossible, since it would have had a weight in the water of over 35 tons. By contrast, the Dynex Warp rope weighed 740 kilograms in water, thanks to its relative density of 1.1. This reduced weight affects not only the lifting operation but also the stability of the vessel and its deck load capacity.

The operation used a 12-strand braided rope with a diameter of 46 millimeters. It has the same strength as a steel rope with the same diameter, DSM Dyneema said.


Nord Stream Pipeline Project Completed Ahead of Schedule
NCS Survey (Aberdeen, Scotland) recently completed a survey contract for Saipem S.p.A. (Milan, Italy) for pipelay support during the inshore phase of the Nord Stream Pipeline Project, two gas pipelines linking Russia with the European Union via the Baltic Sea.

Two small vessels were mobilized with NCS Survey’s real-time 3D SVS (subsea visualization system) for touchdown monitoring, operating from the four-meter contour at the beach pull-out to the intermediate lay-down locations.

Working on a 12-hour rotation, the two vessels transmitted continuous live video images and data of the touchdown point to the C10 barge engineer, giving the accurate touchdown position of each pipeline in real-time as they were laid into the pre-excavated trench. Pre-lay and post-lay surveys were also performed, with field charts being completed within 24 hours by two survey personnel.


Gibdock Repairs Collision-Damaged Cargo Ship
Gibdock (Gibraltar) recently repaired the three-year-old multipurpose general cargo/container vessel Ems, owned by Werse Schiffahrts (Münster, Germany), after a collision damaged the vessel.

The 94-meter-long, 5,500 deadweight tonnage Ems had been alongside the port of Montril, near Almeria, Spain, when the vessel was struck by the bulbous bow of the ferry Ace 2, which had broken free from its moorings. Ems was effectively sandwiched between the Ace 2 and the quay wall and in the process suffered significant damage to both its port and starboard sides.

The rogue vessel’s bow punctured the Ems’ hull, causing a large five-by-four-meter hole. Significant damage was also done to the fuel tanks, main deck, cargo hatches, coamings, hatch covers and gangway.

The Ems arrived in Gibraltar in early December. In all, Gibdock used some 22 tons of steel to repair the hole in the vessel’s side and other work was performed during a 14-day period in Gibdock’s No. 3 drydock. The ship was redelivered on time to the owner, in line with the original specification. On leaving the drydock, the Ems remained at the yard for a further period of alongside repairs and maintenance to hatch cover hydraulic systems.


2012:  JAN | FEB | MARCH | APRIL | MAY | JUNE | JULY | AUG | SEPT | OCT | NOV | DEC
2011:  JAN | FEB | MARCH | APRIL | MAY | JUNE | JULY | AUG | SEPT | OCT | NOV | DEC


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