Estonia’s first electric ferry to sail with Steerprop units in 2028

Estonia’s first fully electric passenger ferry will use two next-generation Steerprop contra-rotating propulsion units, combining battery power for routine crossings with capability for demanding Baltic conditions. Ordered from Poland’s CRIST shipyard, the vessel is scheduled to enter service on the Virtsu–Kuivastu route in late 2028. Biodiesel generators will provide backup.

Two SP 25 CRP units with permanent magnet motor drives will propel the ferry. Steerprop’s equipment is scheduled for delivery in late 2027, ahead of the planned operational debut the following year. The approximately 95-metre vessel will carry up to 380 passengers and either 110 passenger vehicles or eight freight trucks.

A three-megawatt-hour battery system will store shore-charged electricity for normal operations. Biodiesel generators will support extended voyages, severe weather and emergencies. The stated range of at least 1,000 nautical miles applies to operation with generator support.

The ferry will introduce Steerprop’s next-generation CRP configuration, which uses pressure lubrication as standard in smaller applications. Replacing immersion lubrication reduces mechanical losses. Steerprop reports an improvement of about 3.5 percentage points in the propulsion equipment’s mechanical efficiency, alongside the system’s established thrust characteristics. That figure describes mechanical efficiency of the equipment.

The supplier says the configuration was chosen for its ability to deliver thrust in ice, wind and open water despite limits on propeller diameter. In a CRP system, two propellers on the same axis rotate in opposite directions. The second propeller recovers rotational energy left in the first propeller’s wake and converts part of it into useful thrust, reducing energy lost in the swirling water behind a conventional propeller. Sharing the load between two propellers can also reduce loading on each one. Steerprop combines the arrangement with azimuth steering so thrust can be directed for manoeuvring.

For a battery-powered ferry, propulsion efficiency affects how much stored electricity each crossing requires. Lower losses can support the operating plan without relying only on extra battery capacity. The company’s CRP technology is used in electric, hybrid and conventional arrangements, so the propulsor is one part of the ferry’s wider energy system.

The Estonian State Fleet signed the design-and-build contract with CRIST on 20 May 2026. The agreement is valued at €49.93 million, with €28 million from the European Union’s Modernisation Fund and the balance supported by national carbon-allowance revenues. LMG Marin France is designing the ferry as CRIST’s subcontractor and has also worked on vessels already serving the Virtsu–Kuivastu connection.

Under the funding conditions, the new ferry must be 64% more energy-efficient than the reference vessel Regula. That target is a project requirement. The vessel is specified to ice class 1B, and the design is intended to maintain island connectivity through changing seasonal conditions. Its generators also provide flexibility for longer crossings and service beyond the primary route.

On 14 October the Estonian State Fleet announced that the proposed ferry had completed its first model tests at the Schiffbau-Versuchsanstalt Potsdam research centre in Germany. The week-long programme used an 8.2-metre model fitted with scaled replicas of the planned propulsion equipment and examined resistance, hydrodynamic behaviour and propulsion performance. The authority reported energy consumption within contractual limits, with a margin remaining. Results indicated performance corresponding to 14 knots, compared with the contract’s 12-knot maximum-speed requirement.

These findings come from model testing and will inform further design refinement before construction. Ice-model tests are planned in Finland in late November to examine performance in level ice and broken ice. Together, the programmes will help assess how hull form, propulsion and energy demand interact.

The project shows the combined engineering required for ferry electrification: batteries supply the energy, while hull efficiency, propulsion, charging and winter capability determine how reliably that energy can support daily service. Normal Virtsu–Kuivastu crossings are intended to use battery power, with biodiesel generators for backup and extended range. Operations are planned to begin in late 2028.