Retrofitting towards climate neutrality

Marine propellers, a complex and important structural part of a ship, have traditionally been made off expensive Nickel-Aluminium-Bronze (NAB) or Manganese-Aluminium-Bronze (MAB) alloys in order to operate under high cyclic loading underwater and withstand high stresses due to cavitation phenomena. These propellers require precision machining, long production times and are very heavy to transport.

All the above result in propeller prices that are typically in the hundreds of thousands of euros and long lead times that can results in ships being stranded (for example, after an accident where the propeller is lost and require replacement). This provides a challenge for small and medium-sized shipyards where ships can be alongside awaiting parts, tying up valuable space in the yards, or require the yards to hold stock of replacement parts to ensure quick turnaround of vessels. The process of changing the propeller, or even individual blades of NAB or MAB propellers, requires either a dry-dock to remove and replace the propeller or a specially trained group of divers to replace blades manually underwater. Besides, a number of issues have been identified with the current NAB/MAB propellers, including vibration, electric signature, and excess weight.

CoPropel puts forth a holistic approach in the shipping industry by introducing a composite marine propeller offering corrosion resistance, light weight, tailoring of material properties, low electric signature and acoustic properties.

The CoPropel consortium seeks to contribute to the optimisation of propulsion systems by developing and maturing technologies for the realisation of marine propellers made of advanced composite materials. Compared to their traditional counterparts, marine composite propellers are more ‘quiet’, ‘lightweight’ and ‘highly efficient’:

  • Low vibration: reduced noise emissions: Its high damping performance absorbs vibration on the shafting leading to reduced underwater radiated noise (URN)
  • Lightweight: 50-60% lighter enabling a smaller shaft diameter resulting in a smaller moment of inertia (1/4)
  • High performance: 12% to 15% lower energy consumption and reduced environmental footprint
  • High Strength: Greater resistance to fatigue enabling high reliability
  • Reduced cavitation: Its flexible deformation enables the cavitation inception to be restrained


In order to promote the competitiveness of the European industry, the CoPropel project proposes innovations in the use of composite materials and the adoption of sensorised structures for future marine applications. Composite materials are gaining significant relevance in different industries and sectors due to performance benefits over traditional materials. The industry players and researchers are making substantial efforts toward innovations and product development to broaden the scope of composite materials across the industries. Following this path traced by composites industry players and researchers, the CoPropel project attempts to produce a set of potential impacts in the short-term, mid-term and long-term.

Although the expected impacts are related to technical achievements and business opportunities for the maritime stakeholders, others such as socio-economic impacts are foreseen:

  • Overcome the limitations of composite materials in the maritime industry by proposing innovations in design, shipbuilding and life cycle management.
  • Generate a new EU-market and regulatory framework to build complex marine propulsion components in composite materials enabling a new sector in the shipbuilding industry.
  • Obtain relevant advances beyond the traditional methods of composite-based vessel design and production, allowing the exploitation of new solutions and procedures in the existing market.
  • Enhance the competitiveness of the European shipbuilding industry and take advantage of the existing companies which are providing solutions of composite materials to other sectors such as aeronautic, automotive and wind energy, among others.
  • Maintain the European leadership position in high added-value vessel design and shipbuilding industry.
  • Improvement in vessels’ safety conditions to novel inspection and maintenance concepts. Develop long-term damage control and health monitoring systems of vessels
  • Reduce the environmental impact of the maritime industry, complying with the European environmental policies regarding Gas Emissions (Directive 2012/33/EU) and Underwater Noise Impact (Directive 2008/56/EU).

More information about the project can be found at the project website