On July 10, 2025, the fully electric passenger vessel “Insel Mainau”, powered by solar energy, completed a record-breaking range test on Lake Constance. Over the course of 19 hours of continuous sailing, the catamaran covered 211.3 kilometers, retaining 20% battery capacity by the end. The vessel returned to regular service the very next day.
According to shipping company Bodensee-Schiffsbetriebe GmbH (BSB), the vessel could potentially cover up to 300 kilometers under optimized conditions. Another test voyage is already scheduled for 2026 to explore how to maximize energy efficiency and use current patterns on the lake.
“Insel Mainau” is the first fully electric vessel in the region to demonstrate such a significant range. The 30-meter-long and 8-meter-wide catamaran was designed and built in 2021 by Ampereship GmbH, a subsidiary of Ostseestaal GmbH & Co. KG, commissioned by BSB.
The vessel is equipped with an innovative energy concept, including proprietary control and optimization software, a magnetic mooring system, and — for the first time — bifacial solar modules developed by ISC Konstanz e.V., capable of generating renewable energy from both sides of the ship.
Since its founding, Ampereship has become one of Europe’s leading manufacturers of solar-powered electric vessels for professional inland navigation. Its latest flagship project is a fully electric ferry for the island of Helgoland. The lightweight aluminum hull of the “dune ferry” — optimized for hydrodynamics — ensures high energy efficiency, long service life, and is fully recyclable.
