VESSEL REVIEW | Insel Mainau – German operator welcomes battery-powered lake ferry to fleet

Bodensee-Schiffsbetriebe (BSB), a transport company that operates in the city of Konstanz in southern Germany, has taken delivery of the first in a series of two aluminium-hulled electric ferries.

The catamaran vessel has been named Insel Mainau ("Mainau Island") after an island in Germany's Lake Constance. It was built by local shipyard Ostseestaal and its subsidiary Ampereship for operation on Lake Uberlingen, the lower portion of Lake Constance that sits between the ferry's namesake island and the coastal town of Uhldingen-Muhlhofen. A catamaran design was chosen to ensure greater space for passengers and a smaller wake during transits while aluminium was selected as the hull construction material due to its lightweight properties.

The new ferry has an LOA of 33 metres, a beam of nine metres, a draught of approximately 1.26 metres, and capacity for 300 passengers and 18 bicycles on two decks with the upper deck being an open-air space. The passenger spaces are also barrier-free to allow greater movement for individuals with limited mobility. The onboard toilets also include those for limited mobility use.

The ferry is notable for its propulsion system, which draws power from onboard lithium polymer batteries with a total capacity of 1,100 kWh and an array of solar panels installed on the roof. This arrangement drives two 75kW rudder propellers to deliver a service speed of eight knots. Charging of the batteries can be done overnight with the aid of a shore power connection. During days of pleasant weather, the solar panels can provide continuous charging even while the ferry is underway.

The propulsion setup also includes two 20kW bow thrusters.

BSB has an option to order a second ferry from the same series. If the option is exercised before the end of this year, the sister vessel will enter operational service in 2025.