DNV GL has certified new controllable pitch propellers equipped with a water-based hydraulic system, developed by Germany’s Otto Piening , a member of Deutsche Yachten.

The environment-friendly propellers, which are the first of their kind, use a water-based hydraulic system instead of oil.

Following the certification, the controllable pitch propellers can now be used in the megayacht market as well as research, naval and coastguard vessels.

"The new non-flammable propeller system does not pose any risk to the environment."

Otto Piening noted that water as a hydraulic fluid offers a cost-efficient solution that is readily available and can be stocked easily.

In the case of a system leak, the new non-flammable propeller system does not pose any risk to the environment and the vessel will be able to continue its journey.

The entry of seawater into the hydraulic system is also seen as less critical than other conditions.

Otto Piening has noted that the development of the new system requires over two million pitch adjustment cycles under full power, and one and a half years of in-house development work.

Wear and tear of the system, which is waiting to receive a patent, has been found to be at a low level.

Blades can also be mounted to the inside or outside of the new propellers' hub using bolts as required, or pursuant to regulations.

Using a five-blade controllable pitch propeller mounted on a 650mm hub, a series of tests has been performed under the supervision of DNV GL.

The forces generated during testing were equivalent to an output of 3,300kw at 440rpm.

Otto Piening has also received approval from DNV GL for a range of four different oil-lubricated controllable pitch propellers.

Image: DNV GL and Otto Piening officials. Photo: courtesy of Otto Piening GmbH.