NEW Guidance Note for propellers made of composite materials
Metals have long been the material of choice for propellers across ship types, but recently composite materials have been seen as an alternative.
This a crucial development, as new environmental regulations are putting pressure on ship owners and operators to find solutions for limiting fuel consumption and underwater radiated noise (URN). By using composite materials – which are lighter and more flexible – for propellers, marine stakeholders have a way to meet these evolving requirements.
To support ship owners and equipment manufacturers, Bureau Veritas began developing guidance note NI 663. The note defines requirements for all stages of designing, testing, certifying and installing propellers made of composite materials.
The benefits of composite materials
Composite materials offer a range of operational advantages for propellers. The material’s flexibility offers new design possibilities that enable reduced cavitation during operation. This limits URN and onboard vibrations caused by traditional metallic propellers.
The resultant quieting effect limits disturbances to marine life, improves the passenger experience onboard ferries and yachts, and helps naval and fishing vessels prioritize stealth.
Propellers made from composite materials also improve hydrodynamic efficiency, due to lightweight blades with controllable deformation. This in turn enables ship operators to limit fuel consumption and minimize the amount of greenhouse gas (GHG) emissions from operations. Ship owners can further benefit from lower maintenance costs, thanks to the material’s corrosion-resistant properties.
Building on industry experience
Since 2016, Bureau Veritas has worked with industry leaders on numerous projects to help manufacturers and ship owners design propellers built from composite materials. We notably participated in FabHeli, a French research project where a composite propeller was tested on a small passenger vessel. Hydrodynamics calculations and FEM models built for the FabHeli project helped us develop requirements for composite propeller design assessment.
We were also part of the Cooperative Research Ships’ COMPROP and COMPROP2 research projects, which explored ways to analyze and design flexible composite propellers. This included studies of cavitation erosion and deformation, a comparative design study with metallic propellers, and scale-model experiments. We were also instrumental in developing ComPropApp, a fluid-structure interaction tool for facilitating design assessment.
Unveiling Guidance Note NI 663
Published in October 2020, Guidance Note NI 663 is the result of Bureau Veritas’ extensive collaboration with industry partners. Our guidelines help propeller manufacturers and ship owners understand all stages of design, testing, certification and installation for composite propellers. It is currently the only Guidance Note released by a classification society that provides requirements for both design and manufacturing assessments.
Looking forward, Bureau Veritas will continue its work on initiatives for composite propeller assessment and improvement. Our continued involvement with research projects RealTide and MEVEF will enable our experts to critically evaluate fatigue and ageing of composite material blades. The results of these studies will likely contribute to future revisions of NI 663.