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Copenhagen Subsea - The Green Advantage

Copenhagen Subsea A/S has introduced a new standard for subsea thrusters with a reliable and sustainable profile.

Allan Nygård Bertelsen, Managing Director of Copenhagen Susbea A/S


Conventional thrusters use oil lubrication for mechanical parts and for pressure compensation in the cavity between the rotor and the housing. In contrast, Copenhagen Subsea’s thrusters use only the surrounding sea water. Manufactured as a unit of two solid molded parts, there is no enclosed space or cavity in the thruster that needs pressure compensation. One of the advantages in relation to conventional thrusters, – which use a fluid for pressure compensation, is of course that the new solution is 100% pollution-free and spillage will never occur.

What is even more surprising, however, is that water functions as good as, or even better, than oil in the permanent and necessary lubrication process in the operating thruster. In the groundbreaking article ‘Water lubricated bearings,’ S. Hother-Lushington concludes that:

“Provided the bearing and its lubrication system are designed properly, the reliability of a water lubricated bearing should be as high as or higher than the more conventionally lubricated bearing (and seal) which it replaces.”

Reliability and sustainability – these are keywords at Copenhagen Subsea A/S.

The world has already seen its fair share of oil catastrophes. The images of BP’s burning Deepwater Horizon platform in the Mexican Gulf in April 2010 make it clear that the efforts to become greener must affect all industries.

As the world moves towards a greener future, we expect our customers to demand still more reliable and sustainable products. Accordingly, our mission is to develop and manufacture subsea thrusters that will lift the state of the art to unprecedented levels.

Copenhagen Subsea A/S thruster


The new standard for testing subsea thrusters implemented by Copenhagen Subsea A/S dictates a remarkable 1,000 working hours of continuous operation at maximum power. Once tested and validated, the thruster must still maintain full functionality and unaffected performance.

When operating in open water, the cost of a failing subsea thruster is critical. Every malfunction, delay or maintenance-break related to the subsea exploration vessel will set back the entire operation.

Right from the beginning, Copenhagen Subsea has been striving to extend maintenance-free operating time well beyond 1,000 hours to secure optimal functionality for its customers.


At its premises in Copenhagen, Copenhagen subsea performs a continuous test of its thrusters. 1,000 hours of operating time comprise 42 days during which the thruster operates 24/7 at maximum power. During this period, the thruster is constantly monitored for performance and energy consumption, and any deviance is registered.

When reaching the significant milestone of 1,000 operating hours, the thruster is carefully examined and, must show no signs of exhaustion or corrosion, and must maintain full functionality and unaffected performance.

The subsea industry is clearly pressing for higher reliability standards. With time, Copenhagen Subsea expect the 1,000 hour test to become the valid standard for a reliability certification of subsea thrusters.

Copenhagen Subsea A/S Thruster in transport casing - ready for shipment.


The thruster is just as critically important as any other component on board the subsea vehicle. For years, however, thrusters have suffered from having the lowest reliability factor among vessel components. Thus, the thrusters have become the weakest link in the chain of operation - with considerable maintenance costs as a result.

Customer applications for Copenhagen Subsea in the subsea industry ranges from ROV, manned submersibles, cleaning robots and AUV: “The customers continue to return to us for discussions regarding robustness, maintenance and spare-part strategies.

These are all issues related to reliability, and they are indeed the most important concerns that our customers express. To us, these discussions confirm that we have made the right choice when investing in developing reliable thrusters to meet the demands of an industry that is becoming increasingly aware of the reliability and sustainability of thrusters in subsea exploration.

Right from the beginning of our development process, we have been convinced that we needed to aim for ambitious goals. Goals that would distinguish us from all other manufacturers of subsea thrusters. By producing evidence that we have fulfilled this goal, we have reached an unprecedented and remarkable milestone in the process of improving reliability, sustainability and reducing maintenance costs in the subsea industry.” Says Allan Nygård Bertelsen Managing Director of Copenhagen Subsea A/S

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