Reliable Operation at 3,000 Metres
Hai Yang Shi You 285 (HYSY 285) is one of China’s most capable deepwater subsea construction vessels, built to operate at depths of up to 3,000 metres and support some of the country’s most complex offshore energy projects.
Delivered by CSSC’s Huangpu Wenchong Shipyard and commissioned by COSL and CNOOC, the vessel plays a central role in subsea installation, flexible pipe laying, saturation diving and ROV-based intervention work across China’s expanding offshore fields.
Designed for continuous, high-load operations far from shore, HYSY 285 represents a new generation of multipurpose deepwater vessels, combining heavy construction capability with precise station keeping and long-endurance performance in demanding offshore environments.
Key Facts
Powering Deepwater Precision
At the heart of the vessel’s performance are six Bergen B32:40L6A medium-speed engines, delivering a combined output of 17 MW. The engines supply reliable electrical power for dynamic positioning, propulsion, cranes, ROV systems and onboard mission equipment, supporting complex subsea operations where stability and redundancy are critical.
Selected for their durability, efficiency and long service intervals, the Bergen engines enable HYSY 285 to operate continuously with minimal downtime, even during extended deepwater campaigns.
Enabling China’s Firsts in Deepwater Development
In 2021, HYSY 285 played a central role in installing the subsea production system for the Liuhua 29-2 field, China’s first deepwater static umbilical project, at water depths of approximately 800 metres. The vessel laid more than 15 kilometres of umbilicals incorporating nine super duplex stainless steel tubes, enabling reliable gas production to support energy supply for millions of households while contributing to emissions reductions through cleaner gas infrastructure.
Since then, HYSY 285 has continued to support subsea installation, commissioning and maintenance campaigns across China’s offshore portfolio, reinforcing its position as a cornerstone asset for deepwater development.
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