Estonia Electric Ferry to Combine Steerprop Propulsion with Battery Power

Summary

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

Propulsion equipment selected for island ferry

The Estonia electric ferry project has selected Steerprop’s latest contra-rotating propeller technology as development progresses towards construction and entry into service.

Two SP 25 CRP units with permanent magnet motor drives will propel the vessel. Steerprop’s equipment is scheduled for delivery in late 2027, ahead of the ferry’s planned operational debut the following year.

The approximately 95-metre vessel will accommodate 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 emergency requirements. The stated range of at least 1,000 nautical miles concerns operation with generator support, rather than battery-only endurance.

Propeller development targets lower mechanical losses

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 approximately 3.5 percentage points in mechanical efficiency, alongside the system’s established thrust characteristics.

That figure relates to the propulsion equipment’s mechanical efficiency. It should not be interpreted as a measured reduction in the ferry’s total energy consumption.

The supplier says the configuration was selected for its ability to deliver thrust in ice, wind and open water despite restrictions on propeller diameter.

How contra-rotating propulsion works

A CRP system places two propellers on the same axis, rotating in opposite directions. The second propeller recovers rotational energy remaining in the first propeller’s wake and converts part of it into useful thrust.

This reduces energy lost in the swirling water behind a conventional propeller. Distributing the propulsive load between two propellers can also reduce loading on each individual propeller.

Steerprop combines that arrangement with azimuth steering, allowing thrust to be directed for manoeuvring.

For a battery-powered ferry, propulsion efficiency influences how much stored electricity is required for each crossing. Lower losses can therefore support the operating plan without relying solely on additional battery capacity.

The company’s CRP technology is used across electric, hybrid and conventional propulsion arrangements, making the propulsor one component of the ferry’s wider energy system.

Earlier construction contract established funding

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 provided through 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. The designer 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 is a project requirement, rather than an operating result already achieved.

The vessel is specified to ice class 1B, with its design intended to maintain island connectivity through changing seasonal conditions. Its generators also provide flexibility for longer crossings and service beyond the primary route.

Model testing provides another development milestone

Separately, the Estonian State Fleet announced on 14 October 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. Tests 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 concern model testing, rather than full-scale sea trials. They 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 the interaction between hull form, propulsion and energy demand.

The project illustrates 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.

FAQs

Who is building the ferry?

Polish shipyard CRIST is building it for the Estonian State Fleet, with design by LMG Marin France.

When will it enter service?

Operations are planned to begin in late 2028.

Will it operate entirely on batteries?

Normal Virtsu–Kuivastu crossings are intended to use battery power. Biodiesel generators provide backup and extended range.

What does CRP mean?

Contra-rotating propellers: two propellers rotate in opposite directions to recover energy and improve thrust efficiency.

What is the construction contract worth?

The design-and-build agreement is valued at €49.93 million.