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Offshore specialist sees growing role for autonomous survey vessel

Fri 31 Aug 2018 by David Foxwell

Offshore specialist sees growing role for autonomous survey vessel
DriX was extensively tested on the Gwynt Y Mr offshore windfarm operated by Innogy Renewables UK Ltd

Offshore specialist Bibby HydroMap says an autonomous unmanned vessel could reduce the cost of conducting surveys on windfarms and has completed testing of DriX, an 8-m autonomous unmanned unit developed by iXblue

Designed to provide an extension of survey capability from shallow and inshore waters to a full offshore environment, Bibby Hydromap described DriX as a new type of autonomous unmanned vessel it believes can rival the performance of a conventional survey vessel.

The versatile system has the ability to accommodate a hydrographic and geophysical survey payload and to aid positioning of underwater vehicles, facilitating data collection on a variety of marine projects.

iXblue business development manager Guillaume Edeline said We were able to jointly demonstrate the relevance of our AUV in maximising efficiency in an offshore wind environment. This really was a milestone for DriX, proving its versatility, the accuracy of its data gathering and its stability in a range of sea states.

The purpose of the trials, run over five days, was to rigorously test the performance and survey capabilities of DriX in a demanding environment. Testing took place in and around the Gwynt Y Mr offshore windfarm operated by Innogy Renewables UK Ltd.

The 576-MW offshore windfarm is in a tidally-challenging area off the North Wales coast and is the fourth largest operating offshore windfarm in the world.

Specific locations of interest were identified within the windfarm to provide a direct comparison with conventional survey methodologies. Fitted with a Teledyne RESON Seabat IDH T50 multibeam echo sounder, the system acquired clean bathymetry at speeds greater than 8 knots, remaining on the intended survey line in cross-tides in excess of 1.5 knots.

With a unique hydrodynamic gondola housing the payload, DriX has been designed to reduce the amount of aeration around the multibeam echo sounder. During trials, a significant improvement was realised when compared to the conventional deployment methods seen with the majority of vessel-mounted multibeam echo sounder systems.

During operations, QPSs Qimera Live was running on board DriX,  but controlled by technical staff on the support vessel, enabling the fully-processed multibeam echo sounder data to be downloaded straight from DriX at the end of each mission.

The data was processed in real-time from the support vessel with very little need for further processing ashore, shortening processing timescales and speeding up delivery of critical information.

Bibby Hydromap said the overall performance and data collection capability of DriX exceeded expectations, providing exceptional manoeuvrability within the windfarm and easy operation and control throughout. It also provided excellent data quality at increased speed, excellent performance in challenging sea conditions and was easily deployed to the site.

Able to operate at speeds of up to 14 knots, with enhanced manoeuvrability leading to line turns of less than one minute, DriX could minimise time spent in the field compared to conventional vessels, said Bibby Hydromap. The reduced profile of DriX both above and below the waterline enabled continuing operations in conditions that would have been unsafe for conventional vessels, where sea states and tidal currents would have limited the closest point of approach to fixed structures and limited data quality.

The company said it feels confident that DriX has the potential to significantly reduce survey and operational costs for asset owners and operators in the future, while reducing the exposure of offshore staff to the marine environment.

DriX has far exceeded our expectations in terms of data quality and performance, and we are delighted to be able to pass this level of quality on to our clients, the company concluded. The level of manoeuvrability both in open water and when in close proximity to fixed structures enables excellent productivity, dramatically reducing acquisition time. Being able to rapidly deploy DriX anywhere in the world will let us meet our clients requirements on short notice, while simultaneously reducing HSE risk and improving output.

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