CJR offers a wide range of products for all sterngear applications. We pride ourselves on providing high quality products that are tailor made to your requirements. Whether you need off-the-shelf or fully bespoke turnkey systems, we will deliver the solution that perfectly meets your requirements. Our aim is not just to offer you the ultimate in propeller and sterngear systems but to empower you to minimise build times and production costs and maximise productivity, profitability and customer satisfaction.
To assure highest dimensional accuracy our propellers are moulded using patterns printed by 3D rapid prototyping printer – the most innovative way in pattern making. For higher volumes, aluminium or resin boxless systems are used. Please click on the link to read more about pattern making.
Over recent years we have also invested in leading edge machining equipment and have developed our own CAD/CAM software and 3D modelling systems. Computer modelling allows for manufacturing to be simulated even before a pattern is made and a test casting produced, ensuring that manufacturing processes consistently deliver optimum results. They are normally cast in nickel aluminium bronze from our highly accurate tooling. The propellers are either CNC machined or hand finished from the precise castings. They are then dynamically or statically balanced and MRI scanned to achieve up to Class S standards for optimum performance and smooth running.
Propellers can be manufactured with standard keyed hubs tapered to: ISO 1:10 , SAE 1:16, BS marine standard 1:12, as well as keyless hub tapered 1:30. Any other non-standard taper can also be machined
Shaft brackets (A or P bracket/Strut) are typically manufactured from high grade nickel, aluminium bronze or manganese bronze materials. Cast in our own foundry with the latest technology casting processes.
The casting process is controlled to IACS requirements including material analysis and NDT testing when needed. Most castings are machined on the latest 5 Axis Machining Centres. Machining in one loading allows CJR to achieve the highest standard of accuracy for alignment of palm mounting to shaft bore. All castings are finished to the highest standard and are fitted with water lubricated bearings which can be IACS approved when required.
Alternatively all brackets can be fabricated in aluminium, stainless steels, or mild steel as a complete item or component parts.
Most shafts are manufactured with Marinemet 25 as standard, which is stronger and more resilient to corrosion than even surgical stainless steel. Other materials from 316L up to Super Duplex are available if required.
Generally, materials are sourced from mills specifically chosen by CJR for their quality to meet IACS requirements.
Shaft sizes are available up to 180mm diameter and a length of up to 9m.
Rudder profile and sections are carefully selected to specific regime of the flow around sterngear.Streamline low drag sections are used for low and medium speed vessels and wedge sections for high speed boats to prevent early stalling. Rudders can be tailored to the hull using the latest design techniques including CFD to determine the accurate flow into the rudder from working propeller.
Detailed hydrodynamic loading is calculated to assess rudder stock and blade strength by FEA as well as supporting bearings reactions. Design and manufacture can be done to any classification society rules including all IACS societies. More about overall design process here.