Propellers that rotate in opposite directions can be good news for large ships

They can provide more than ten per cent better efficiency compared to conventional propellers.

One of the setups investigated in the Sea Zero project was a combination of contra-rotating propellers (the red propellers in the middle of the picture) and two pulling thrusters. A pulling thruster acts as a propeller that pulls the ship forward, much like an aircraft propeller.

(Photo: Brunvoll)

Henriette Krogness Henriette Krogness Henriette Krogness COMMUNICATIONS ADVISER

Presented by: Presented by: Presented by: SINTEF

Published 2 January 2026 - 00:01

Researchers at SINTEF have now designed and built new measuring equipment for testing contra-rotating propellers, which are propellers that rotate in opposite directions.

This could be good news for many large ships.

Researcher Øyvind Rabliås explains that they see higher propulsion efficiency when they utilise some of the energy normally lost behind the front propeller, while the rear propeller also gets better water flow.

"This can provide more than ten per cent better efficiency compared to conventional propellers,” he says.

Although contra-rotating propellers are not new, they are still rarely used on commercial ships.

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The reason has been their cost and more complicated design than traditional layouts. That may be changing now.

“Together with our research partners, we’ve spent a lot of time on understanding and developing solutions for this. Now we believe that the technology is mature and ready for wider use,” says Jahn Terje Johannessen. He is a senior hydrodynamicist at Brunvoll, a leading provider of propulsion and manoeuvring systems.

Promising test results

The new measurement system was developed after Hurtigruten chose contra-rotating propellers for its zero-emission cruise ship in the Sea Zero project. The goal is an emission-free Hurtigruten ship with a sustainable and circular solution by 2030.

Contra-rotating propellers have significantly better efficiency than today’s propeller systems.

This video shows how the propellers spin in opposite directions during a test run at the Norwegian Ocean Technology Centre.

“This design simply means that we need less energy to achieve the same speed compared to conventional propellers. Brunvoll’s design is also more efficient than the contra-rotating propellers that exist today,” says Gerry Larsson-Fedde, chief operating officer at Hurtigruten.

From drawing board to reality

A broad interdisciplinary team at SINTEF Ocean – technicians, instrumentation engineers, design experts, and researchers – worked together to create the new tools for model-scale testing of contra-rotating propellers.

The result is a system well suited for self-propulsion tests.

Two dynamometers, which are instruments used to measure force in rotating systems, have also been developed.

“One version is suitable for integrating into ship models that are tested in the Towing Tank, and the other version is used in open water tests and in cavitation tests,” says Rabliås.

Model of Hurtigruten’s new cruise ship during testing in the ocean basin.

The system has already tested Brunvoll’s propeller system for Hurtigruten.

The results provided valuable insight into the system’s performance and helped identify the most efficient propulsion solution for further development.

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“It was an added bonus for Brunvoll that the project is so versatile. We have a lot of different industrially relevant issues in our work to create a demonstrator,” says Johannessen.

Hurtigruten is also very pleased to have its ground-breaking ship tested.

“It’s fantastic for us that we can test all the parts of the Sea Zero design at such a professional and advanced laboratory as SINTEF has. Contra-rotating propellers are new to us, and they are not common on ships either. That’s why it's so important for us to be able to thoroughly test the ship design in the cavitation tunnel. Then we’ll know that it will work in practice,” says Larsson-Fedde.

Some challenges remain

Propulsion efficiency is increased by recovering part of the energy loss from the front propeller and by better inflow to the rear propeller. This is why gains of more than ten per cent are possible.

However, contra-rotating propellers require a complex shaft-in-shaft system.

“The design process is also more complicated than for conventional propellers, both because of complex flow phenomena and the larger number of parameters that need to be adjusted, compared to one propeller," says Rabliås.

He explains that this applies, for example, to the diameter ratio and the propeller’s revolution ratio between the two propellers.

“The goal of Sea Zero is to design the world’s most energy-efficient ship, and in that quest we have to leave no stone unturned. The propulsion itself uses a lot of energy, and so contra-rotating propellers are very exciting for us to look at,” says Larsson-Fedde.