Classification society DNV has outlined key lessons from the world's first methanol retrofit of a 20,000 TEU container vessel, completed at CHI Shanghai in September 2025, reports Singapore's Manifold Times.

The seven-year-old ship, nearly 400 metres long, became the first mega container carrier converted to run on methanol. The project involved Cosco Shipping, CHI Shanghai, MARIC, suppliers, and DNV, and was delivered on time and at an industrial scale.

The conversion required fundamental changes to the fuel system, which was originally designed for conventional fuels. MARIC developed the general design, while CHI Shanghai handled detailed engineering and acted as the EPC contractor.

The scope included converting the MAN B&W 11S90 main engine and two Wartsila auxiliary engines to dual-fuel operation. New methanol tanks with a capacity exceeding 15,000 cubic metres were installed forward of the engine room, along with new fuel preparation and supply systems.

DNV stated that early planning and close collaboration were critical to overcoming challenges in design integration, construction, and commissioning. The retrofit demanded innovative construction sequences and tight interface management due to confined spaces and existing structural arrangements.

Yan Hao, commercial director at CHI Shanghai, emphasized that coordination was vital, as it was the first time all suppliers had worked together on a methanol retrofit of this scale. He described the project as highly complex, involving engine makers, fuel system suppliers, and safety specialists.