Innovative underwater vehicle developed for subsea cable burial

itatsmicroShotts, Scotland, based subsea services provider Pharos Offshore Group. has started construction of a new remotely operated vehicle (ROV) designed specifically for the offshore wind farm cable market.

The new Inter Turbine Array Trencher, the ITAT 800 (TM), is an 800 HP (600 kW) self-propelled trenching ROV that can be more easily maneuvered by the operators onboard its support ship than a towed plow.  It uses a unique water jetting technology to cut the seabed. This is safer than a metal plow share or mechanical cutter around the valuable power cable. The water jets fluidize the sea floor materia, allowing the interconnecting power cables of a wind farm to sink in up to three meters deep.

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Using a trenching ROV like the ITAT 800 can give wind farm developers and cable installers more scheduling flexibility than with conventional cable plows. The inter-array cable can be laid on the sea floor to connect the wind turbines more quickly and then a Post Lay Inspection and Burial  (PLIB) process is used to complete the burial process using a trenching ROV.

Subsea cable burial ensures cable protection in distribution systems worldwide and is widespread best practice in the telecoms industry. Left unprotected, power cable, fiber optic telephone cable and oil and gas pipe is vulnerable to damage from ship anchors, fishing activity and other threats.

The design of the ITAT 800 has been a priority for Pharos Offshore Group to meet demand from customers for safer trenching methods, particularly for the offshore wind market. The need for extreme care when operating around the inter turbine array cable, also called infield cable, is due to the multiple short runs of cable within a confined, precisely planned area of the turbine foundation array. The installation and burial processes currently being used have resulted in many insurance claims being made by offshore developers to cover the costs of damage to cables.

"We are excited to bring together the expertise of our operational personnel and designers, with the construction of the ITAT trenching ROV. We think this will fulfill a critical need of the growing offshore wind farm market," says Phil Walker, CEO of Pharos Offshore Group.

The ITAT 800 is about the size of large car. The concept and the design have been developed from the experience gained from many tens of thousands of kilometers of cable burial in the telecoms and oil and gas sectors. It is built using many proven and readily available Commercial-Off-The-Shelf (COTS) parts. This reduces the system's initial price tag, and helps keep ongoing operating costs low. The ITAT's maneuverability, survey equipment, low profile and jetting power provides the flexibility required for infield cable work.

The cable maintenance version of the ROV named the MENTOR 800(TM) provides the ITAT's powerful jetting capability to depths up to 3000 meters for deeper cable and O&G pipeline work. Interchangeable tooling systems provide the flexibility to accommodate the most demanding undersea cable installation and maintenance operations.

Pharos Offshore Group. plans to sell and lease multiple vehicles to serve Round 3 wind farm projects in the United Kingdom and upcoming projects in North America.

August 24, 2011

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