One of the world’s biggest diving support vessels has re-entered service after an engine overhaul that included having key components tested and repaired at a remote workshop.
The engines and turbochargers on the 140m long Seven Atlantic, owned by Subsea 7, were serviced 10 years after the vessel was built, with Royston Diesel completing the work. Seven Atlantic is powered by six 3,360 kW Wärtsilä W7L32 engines running on marine gas oil, each paired to a 3,360 kVA Van Kaick generator. The diesel-electric arrangement drives three 2,950 kW stern azimuth thrusters, two 2,400 kW retractable bow azimuth thrusters and a 2,200 kW bow tunnel thruster.
One of the engines was disassembled to install new cylinder heads, air start valves, indicator cocks, injectors, and cylinder seals. Relief valves, pistons and conrods, cylinder liners, bearing blocks, crankshaft and turbocharger were sent to UK headquartered Royston’s Newcastleworkshop for checking and essential repair work before being returned ahead of the final reassembly and inspection of the engine.
Engineers also overhauled the turbocharger on another engine. The NA297 Napier turbochargers from both engines were removed, stripped, cleaned, inspected and balanced at Royston’s dedicated turbocharger facility. Following the service, incremental load testing in line with the engine manufacturer’s specification was also completed by engineers.
Royston service manager Shawn Doering said that the company’s experience with the engine and vessel type ensured a quick re-entry into service. Shipowners can save up to 30% on the cost of overhauls by using third-party service providers instead of OEM services, he said.
Seven Atlantic has a a 24-person saturation diving system as well as a 120-tonne heave compensated crane. The vessel’s DP3 system is designed to support diving operations in wave heights of up to 4.5m. This requirement led to an unusual propulsion layout, with three engine rooms housing two diesel generator sets and three switchboards each.
Intelligent Monitoring & Maintenance is a new category in this year's Marine Propulsion Awards. Make your nominations by 24 March.