Tokyo, October 18, 2025 — In a landmark move for clean shipping, classification society ClassNK has officially added TEN-OH, Japan’s first hydrogen-fueled tugboat, to its register. The vessel, constructed by Tsuneishi Shipbuilding Co., Ltd., was registered on October 9 following rigorous safety assessments under ClassNK’s Part GF framework for low-flashpoint and hydrogen fuels.
Developed under the Nippon Foundation Zero Emission Ships Project, the tugboat project is part of Japan’s push toward zero CO₂ emissions in the maritime sector. ClassNK’s approval includes evaluates hydrogen-specific risks — such as high ignitability and leakage — and implementing countermeasures to safeguard crew and environment.
How TEN-OH is Built for Safety and Performance
While many details remain proprietary, public disclosures indicate that TEN-OH is outfitted with a twin hydrogen-dual fuel engine arrangement producing around 4,400 horsepower, with about 250 kilograms of hydrogen stored aboard in high-pressure tanks. The system allows fallback to conventional fuel if needed, helping to bridge the operational safety gap as hydrogen propulsion matures.
Key to this registration was ClassNK’s application of its Part GF “Rules & Guidance for the Survey and Construction of Steel Ships”, tailored to low-flashpoint and alternative fuels. This ensured thorough inspection of hydrogen storage, piping integrity, leak detection, ventilation, ignition prevention, and crew safety measures. ClassNK will monitor TEN-OH in service and incorporate lessons learned into evolving international standards.
Significance for Greener Shipping & Port Emissions
Although tugboats are modest in scale compared to large ocean-going vessels, they play an outsized role in local emissions—maneuvering in port, idling alongside docks, and assisting larger ships. Replacing a conventional tug with a hydrogen-fueled one can help curb greenhouse gas and air pollutant emissions in dense port environments.
More broadly, TEN-OH serves as a proof of concept for hydrogen use in commercial ship propulsion, helping de-risk the technology, validate bunkering procedures, inform crew training, and build confidence among regulators, shipowners, and classification bodies.
The registration also signals momentum in aligning maritime operations with escalating regulatory pressure. According to ClassNK’s own “Alternative Fuels Insight” report, international frameworks like the IMO’s 2023 GHG Strategy and regional policies (e.g. EU-ETS, FuelEU Maritime) are pushing shipowners toward zero- or low-emission fuels. A complementary study by EMSA (European Maritime Safety Agency) assesses safety risks and provides guidelines for hydrogen use on ships — underlining that proper engineering and classification scrutiny are key to unlocking scale.
The path ahead for TEN-OH includes operational trials, safety monitoring, and performance benchmarking (fuel consumption, reliability, maintenance). If successful, this could accelerate hydrogen propulsion adoption in other tugboats, ferries, service crafts, and eventually larger vessels.
Equally critical will be the scaling of hydrogen bunkering infrastructure in ports and refueling logistics tailored for marine use. At the regulatory level, insights from TEN-OH’s service will help refine classification rules and contribute to international standardization in hydrogen-powered shipping.
As Editor in Chief of The Maritime, I lead content development, interviews, and digital storytelling across our multimedia maritime platform. With over 10 years of experience in the maritime industry, I create and publish in-depth stories and video features that highlight key players, emerging trends, and operational realities across global shipping. Before launching The Maritime, I worked as a Vessel Operator at Imza Marine A.S., gaining hands-on commercial shipping and voyage operations experience. I also served as Marketing Communications Specialist at Gimas Ship Supply & Services, where I managed corporate communication, digital strategy, and industry outreach for shipowners and maritime clients. I hold a Master’s degree in Maritime Transportation Management from Istanbul Technical University and a Master’s degree in Publishing from Marmara University. My work is driven by the belief that the maritime world deserves strong, informed, and accessible media representation. I am committed to sharing the stories of maritime professionals and contributing to the sector’s visibility, knowledge exchange, and future development.
