Versatile Workboat is a Windfarm Winner

Delta Marine’s Whalsa Lass working off the coast of Grimsby for one of the “Big 6” energy companies

Delta Marine’s vessel Whalsa Lass has demonstrated its versatility during recently completed works on the large windfarm off the coast of Grimsby UK for one of the ‘Big 6’ energy contractors.

The windfarm consists of 73 Vesta V112 3MW turbines located in water depths of some 15m and is now providing electricity sufficient to power up to 170,000 homes.

When the Shetland based operator chartered its Damen 2611 Multicat for a basic remit to serve as anchor handler for the cable laying vessel it had no idea what further scope of services the vessel would be called upon to perform.

The 26m Whalsa Lass features an 11.5m beam for great stability and a shallow 2.25m draft, advantageous for bringing cables to shore. Three Caterpillar C32 TTA main engines generate 1,902 bkW to provide a powerful 37 tonne bollard pull and a speed of 10 knots. A 100 tonne winch and twin Heila3 SL 230t/m knuckleboom cranes further add to a specification which informed client and operator alike that the vessel was capable of making a broader contribution to the project than was first envisioned.

Work started with Whalsa Lass handling a six by 7.5 tonne delta flipper anchor spread for the cable lay vessel, with the anchors pre-laid and the Multicat hooking up to cable lay vessel wires in up to 3 knots of tide. Soon Whalsa Lass was delivering water and provisions to other project vessels within the 25sq/km work area. She was then conducting cardinal buoy inspections, retrieving and returning them to shore for maintenance and subsequently re-deploying them. She was called upon for the delivery of cable protection systems and the deployment of rock bags over cables in shallow water, deploying a 4 tonne bag every 14 minutes. She could be equipped as a dive support platform, with a full dive spread encompassing decompression chamber, welfare, quads, a dive shack and three point mooring, all whilst still conducting anchor handling duties with the dive spread onboard. This allowed her to work with the divers moving boulders clear of the cable lay route. A full ROV spread was also brought onboard, with a 20’ ROV container, control shack, provision of 120A power from ship’s generators and three point mooring, again whilst concurrently still anchor handling. Also performed were PLGR works, dragging a grapple train along the cable route checking for other obstructions which could affect the subsequent cable lay. Whalsa Lass was even called upon to salvage containers lost overboard from a passing cargo vessel which were drifting and posed a collision risk to the windfarm, then transporting them ashore.

Delta Marine created method statements, risk assessments and storyboards for all the above tasks, reducing the workload for the client’s management and minimising delay to works proceeding. Delta sourced all rigging and anchors, replaced all worn or damaged components and provided a weekly inventory to the client detailing the location and condition of each individual component. Delta even extended the push knees at Whalsa Lass’s bow, allowing crew transfer vessels to push on for optimised safe passage of project personnel whilst on site.

Such comprehensive efforts by Whalsa Lass and Delta Marine did not go unnoticed. The client’s cable package manager told Delta: ‘All your efforts have been successful and executed safely and professionally. It was a pleasure having you and your team involved in mobilisation and execution meetings to gain your advice and input. Your team’s positive attitude and ambitious nature have prevented vessel and project down time on a number of occasions. We always knew that the task would be executed professionally when given to Whalsa Lass.

‘From the entire construction team we would like to thank you and your team for all your hard work and efforts over the past year.’