VESSEL REVIEW | Hengyi No 1 – Large semi-submersible fish cage deployed off China’s Guangdong province

Chinese manufacturer Guangdong Blue Water Deep Sea Equipment Technology recently completed construction of one of the largest semi-submersible, offshore fish breeding cages ever to be operated in Guangdong province.

Operated by Guangdong Hengyi Marine Industry Development, Hengyi No 1 (恒燚一号) has an LOA of 101 metres (331 feet), a beam of 47.5 metres (155 feet), a displacement of 2,300 tonnes, and capacity for up to 60,000 cubic metres (2.1 million cubic feet) of water. The structure also boasts intelligent operating and monitoring systems to better preserve the quality of farmed fish even with minimal manpower.

Intelligent features for greater efficiency

The intelligent operating systems direct the cage’s numerous functions such as automatic submersion and refloating, feeding, fish monitoring and identification, dynamic positioning, and control of environmental parameters such as meteorological and water quality data to ensure fish health. Data collected by the operating and monitoring systems are transmitted in real time to shore stations via 4G/5G networks.

Liveaboard facilities are available for eight technicians who will oversee operations. These facilities include cabins, a galley, and a mess. A cold storage compartment is also fitted.

The main rectangular cage structure is divided into six compartments, each of which can hold different species in up to 10,000 cubic metres (350,000 cubic feet) of water. Aquatic species to be farmed using the cage include golden pomfret and octopus. The builder said that the cage will have projected annual outputs of CNY72 million (US$10 million) for golden pomfret and CNY135 million (US$19 million) for octopus.

Flexibility and durability for sustained operations

The cage can accommodate different species simultaneously if needed, thus allowing for maximised utilisation of the available onboard energy supplied by two diesel generators, batteries, and PV panels.

The cage also boasts laboratory space to enable the embarked technicians to perform various breeding techniques and related experiments. This will then help reduce the risk of any identified disease spreading among the farmed fish.

The structure can withstand typhoons and other extreme weather conditions, thanks in part to a ballast anti-slip and mooring system that keeps it secured at specific coordinates.

Design work on Hengyi No 1 was completed in compliance to China Classification Society rules. The cage is presently deployed at the Zhanjiang Donghai Island Marine Ranch in the waters off eastern Guangdong. In the future, when the cage will also be used as an aquaculture tourism platform, up to 50 people can be accommodated on board.