Ship & Boat International eNews: December 2021
Offshore search and rescue (SAR) services provider Zelim has teamed up with naval architect Chartwell Marine to deliver a remotely operated rescue vessel to provide on-site safety coverage for wind turbine technicians. Survivor 1 – the prototype of the Survivor class – would be fitted inside a launch and recovery cradle and attached to a structural connection ring affixed to the wind turbine. In the event of an accident – for instance, a technician or SOV crew member falling off the turbine or overboard – the SAR craft would free fall 25m into the water.
Zelim and Chartwell Marine state: “The increasing distance of projects from shore renders traditional maritime support ineffective. Lifeboats can take several hours to reach the site of the emergency, and even rescue helicopters can take well over an hour.” With offshore wind farms moving further out to sea and into deeper waters, SAR vessel crews also face increased risk when attempting to rescue casualties at these sites.
Built in aluminium, Survivor 1 measures 11m x 4m, weighs 10tonnes and draws 0.8m. The craft’s range exceeds 100nm, meaning it can cover a good distance between neighbouring wind farms, and can operate in significant wave heights of 4.5m – a factor verified, via model tests, by Seaspeed Marine Consulting. A pilot inside a control station, located outside of the offshore environment, controls the Survivor remotely. “The vessel utilises a SARBOX visual, thermal and GPS overlay operation system, and is intended to be remotely operated with AI assistance,” Andy Page, Chartwell Marine MD, tells Ship & Boat International. The craft’s twin waterjets are driven by either an HVO-fuelled diesel internal combustion engine or an electric motor, depending on the operator’s preference. Page adds: “The two waterjets will activate prior to contact with the water, to stop the vessel drifting backwards into the turbine.”
With no rescue personnel physically on board, the Survivor relies on a rescue conveyor system to recover man overboard (MOB) casualties from the water. This feature was designed by engineers drawn from Zelim, Chartwell Marine, Engineered Marine Systems, Seaspeed Marine Consulting and Saviour Medical. Located at the bow, the rescue conveyor is similar to an upwards-moving, step-free travelator: when the casualty makes contact with the conveyor, he/she is carried up onto the craft. This spares the casualty from having to clamber aboard the Survivor, which may not be possible if he/she is injured or rapidly losing body heat.
Typically, Survivor 1 can recover 12 persons in a single mission, though Page says: “In an absolute survival condition, it could take significantly more.” The air-conditioned cabin offers folding seating for 12 persons, plus space for two stretchers. Other features include easy-to-open door handles and a helicopter pick-up zone, so that ill or injured parties can be conveyed from the site to a hospital on shore.
Two sets of free fall tests were conducted at QinetiQ’s Ocean Basin pool in Haslar, UK, allowing the partners to assess the craft’s free-running performance in sea state 6. The next step will be to install a Survivor at an active offshore wind farm. Page reports that Zelim has secured a letter of intent from “two major wind farm developers” for a Survivor-class craft, and a UK boatyard has been contracted to build the first commercial unit, with deployment anticipated in 2022.