Dutch solar technology company Wattlab and Germany’s HGK Shipping have unveiled the Blue Marlin, the world’s first hybrid solar-powered inland cargo vessel. Officially christened in Hamburg on July 3. The 86-meter-long vessel will carry bulk goods for Salzgitter AG, one of Europe’s leading steel producers, across Germany’s extensive canal network.
With 192 solar panels installed, the Blue Marlin can generate up to 37,500 kilowatt-hours (kWh) of electricity each year. For the first time in inland shipping, this solar energy is used not only for onboard systems but also directly to power the ship’s propulsion system.
David Kester, co-founder and COO of Wattlab, described it as “This is a technical milestone,” he said. “The Blue Marlin’s solar panels are connected to both low-voltage onboard systems and the high-voltage propulsion network. This means HGK Shipping can proudly say they are the first inland shipping company to operate a vessel that uses solar power directly for propulsion.”
The vessel also features a diesel-electric ‘Future Fuel Ready’ system, advanced remote navigation technology, and a design that allows operations in shallow waters.
Fabian Gerdes, head of customer logistics at Salzgitter Flachstahl, said, “With this innovative ship, we are continuing our efforts to reduce CO₂ emissions and improve the efficiency and resilience of our supply chains,” he said. “It helps us move closer to climate-friendly transport of steel products and bulk materials. The Blue Marlin will cut our carbon footprint significantly, aligning with our sustainability goals.”
The hybrid solar system works with four diesel generators and uses a process called ‘peak shaving’ to avoid switching on extra engines during periods of high energy demand. This means the vessel can use its energy resources more efficiently and reduce fuel consumption. In certain conditions, such as sailing downstream with a light load, the Blue Marlin could even operate entirely on solar power for short periods.
Florian Bleikamp is the managing director of HGK Dry Shipping. He praised the collaboration with Wattlab and Salzgitter AG. “Together, we are putting bold ideas into action,” he said. “The Blue Marlin uses emission-free solar technology. It also features remote-controlled navigation and resource-saving propulsion systems. This vessel is a powerful symbol. It shows what industry and logistics can achieve when working hand in hand.”
The De Gerlien van Tiem shipyard in the Netherlands constructed the ship. Workers installed the solar panels there in just one week. The rapid installation process shows something important. Builders can easily implement such technology on new builds. They can also add it to retrofitted vessels with minimal downtime.
This project builds on lessons from HGK’s earlier vessel, the MS Helios. The Helios gained global attention in 2024. It had the largest solar panel installation on an inland shipping vessel. The Helios used its 312 solar panels to power only low-voltage systems. However, the Blue Marlin raises the bar. It integrates solar energy directly into its propulsion system.
The Blue Marlin has already earned the prestigious Gold Green Award for sustainable vessel design. It reflects a growing trend in the shipping industry. Companies face pressure to reduce emissions. They also face pressure to adopt renewable energy sources.
Wattlab, known for its scalable maritime solar solutions, believes this project signals a broader shift in the sector. “We see this as a step forward in decarbonizing not only inland shipping but also coastal and seagoing vessels,” Kester said.
The Blue Marlin measures 282 feet in length and 31 feet in width. It also features twin Veth rudder propellers and a bow thruster for improved manoeuvrability. Its modular design allows it to connect with push barges, enabling it to handle cargo loads of up to 3,110 tons, even in shallow water.
The Blue Marlin demonstrates how innovation and partnerships can lead to practical solutions. HGK Shipping operates a fleet of 350 vessels and transports over 43 million tonnes of cargo annually. This latest addition to their fleet strengthens their position as a leader in sustainable inland transport.
“The Blue Marlin shows that sustainable technology is no longer just a vision of the future—it is here and working today,” Kester added. “It’s a sign of what’s possible when technology and industry come together to address climate change.”
