Prominent Role for Geo Focus Vessel in Irish Geophysical Survey Campaign
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Prominent Role for Geo Focus Vessel in Irish Geophysical Survey Campaign

North Irish Sea Array (NISA) Offshore Wind Farm is undertaking a geophysical survey campaign on the proposed NISA Export Cable Route Area, off the coast of north County Dublin and County Meath, Ireland. The campaign started on 3 September and is set to finish on 3 October, weather permitting.

The NISA Export Cable Route Area forms an irregular shape spanning 11km north-south and 18km east-west at its widest point. The survey area has two landfall areas close to Balbriggan and surveys will proceed as shallow as approximately 3m water depth. The NISA is an offshore wind energy project covering around 226.9 square kilometres in the Irish Sea between seven and 17 kilometres off the coast of the Dublin, Meath and Louth counties. Once operational, it will have the capacity to provide renewable energy for up to 500,000 Irish homes.

Multibeam Echosounders, Sub-bottom Profilers and Sidescan Sonar

The survey will be conducted by the Geo Focus survey vessel, surveying in excess of 10m water depth, and the Ros Aine vessel, surveying in water depths of less than 10m. As the survey vessels will be restricted in their ability to manoeuvre when surveying due to the deployment of the towed survey equipment from the vessel for the duration of the survey activities, all vessels operating within the area are requested to keep a wide berth and pass at minimum speed to reduce vessel wash. The vessels will also display appropriate lights and signals.

The survey will utilize multibeam echosounders, sub-bottom profilers, a sidescan sonar and a magnetometer, both hull-mounted and towed. Typically, the towed cable lengths will be about four times the water depth while acquiring survey data. The work will be conducted during 24-hour operations.

Offshore wind farm array area and indicative WTG layout. (Source: North Irish Sea Array Offshore Wind Farm, EIA Scoping Report – Ove Arup & Partners Ireland Ltd)

Selected Survey Vessels

In early 2022, N-Sea Group signed a long-term agreement with Geo Plus to charter the advanced hybrid survey and ROV support Geo Focus, built in 2012 by De Haas Maassluis in the Netherlands. Survey vessels of Geo Plus are employed to scan and map the seafloor worldwide to locate changes in the seabed or to find unexploded ammunition and shipwrecks. The ships are well-equipped for route surveys for pipelines and cables for the oil and gas industry and renewables.

The Ros Aine is a vessel developed to meet ICCB’s (Irish Commercial Charter Boat’s) expanding operational requirements, including surveying, assisting with cable landing and transporting supplies and personnel to near-shore offshore installations, partly in anticipation of large-scale offshore energy projects in Ireland.

Geo Focus survey vessel. (Courtesy: N-Sea)