ClassNK Registers Japan’s First Hydrogen-Fueled Tugboat ‘TEN-OH’

In a breakthrough for Japan’s clean shipping ambitions, ClassNK has officially added Japan’s first hydrogen-fueled tugboat, TEN-OH, to its register. The vessel, built by TSUNEISHI SHIPBUILDING Co., Ltd., marks a major step forward in the nation’s efforts to achieve zero-emission maritime operations.

Developed under The Nippon Foundation’s “Zero Emission Ships Project”, TEN-OH represents a key milestone in Japan’s transition toward sustainable marine propulsion systems. The project is part of a national initiative to advance vessel technologies that completely eliminate CO₂ emissions.

During the vessel’s planning and development stages, ClassNK worked closely with stakeholders to ensure robust safety standards for hydrogen-fueled operations. Applying Part GF of its “Rules and Guidance for the Survey and Construction of Steel Ships,” ClassNK conducted comprehensive reviews to address challenges unique to hydrogen fuel — including explosion prevention, leak mitigation, and crew and environmental protection.

Following the successful completion of all required surveys and safety assessments, ClassNK officially registered TEN-OH on 9 October 2025.

Moving forward, ClassNK will continue to support the tugboat’s safe operation through ongoing inspections and surveys. Moreover, insights gained from this pioneering project will help update industry guidelines, refine international standards, and accelerate the global shift toward decarbonized shipping.

“The TEN-OH demonstrates Japan’s leadership in hydrogen-powered marine innovation and sets a strong precedent for the next generation of zero-emission vessels,” ClassNK noted.