Feature 1 | GEARS AND PROPELLERS A focus on quality


Ship & Boat International recently visited CJR Propulsion’s headquarters in Southampton, UK, and was impressed with the level of technology and sophistication at this family-run business.


A


s the largest producer of propellers and stern gears in the UK, and with a turnover of


£6 million (€10 million), CJR Propulsion is one of


the most technologically


advanced manufacturers in Europe. A recent focus of the company is


the move towards lean manufacturing, and with this in mind, CJR Propulsion has invested more than £2.5 million in leading edge machinery over the last four years; along with reducing its workforce, who are all now multi-disciplined trained.


It is also


planning on investing a further £1.5 million over the next 12 months. CJR uses leading-edge pattern designs


and tooling, and accurately machined patterns which ensures higher quality castings and less material wastage. The company’s newly-developed pattern material composition


guarantees


accuracy and durability. Currently the company is producing 2500 units per year, but as the market is changing its focus towards larger vessels, CJR is also changing, and manufacturing larger propellers. According to sales manager Chris Feibusch, ‘Boat builders are taking us to our limit’. Sunseeker, a user of CJR units, for example, is now requesting propellers for boats that are 11m-13m in length.


Design advances In recent years CJR has altered its way of


thinking with regard to propeller design. Up to two years ago the company was using what Mr Feibusch describes as ‘traditional methods’ but since a new naval architect, Marek Skrzynski, was employed each boat is treated to a custom-designed propeller. This, according to Mr Feibusch, has been a ‘stunning success’.


Mr Feibusch admits that CJR do not


produce the cheapest propellers on the market, but emphasised that the product was engineered to such a high standard, that the company’s strength is its quality, and to that end, its buyers are boat builders with similar values. CJR has modernised the way


propellers are fabricated, and models itself on the aerospace industry. Following in the footsteps of turbine blade engineering, every propeller made has a full balance report, is MRI scanned, is dynamically balanced, has a full pitch report, and is thoroughly checked against the original design. Since January this year, each unit


is fully machined for accuracy and consistency using Mazak Integrex machinery, and Delcam ‘Visual Recognition’ integration software.


Cavitation analysis on a CJP propeller design. The company has full 3D design


capability and uses AutoCAD 2007, Rhino 4.0, Autodesk Inventor II Professional, as well as in-house developed software


for propeller


3D modelling. CJR also utilises a unique programme


developed by the Technical University of Gdansk to support the propeller designing process, and uses a propeller performance prediction program using ‘lifting surface’ theory, which has proven full-scale accuracy. Additionally, a wide range of series propellers are now data tested in cavitation tunnels. CJR has close links with the Wolfson Unit and the Gdansk Model Basin. All these enhancements have


ensured that the company has seen a dramatic improvement in refinement, smoothness, and acceleration of its propellers. Recently CJR launched the custom


M-R-K Superprop propeller. These units are individually tailored to a particular vessel’s specification, and the unique profiles are then optimised to deliver maximum speed, responsiveness, and efficiency. A highly advanced and unique


Casting a propeller in CJR’s foundry. 26 A fully CNC machined resin pattern.


sof tware programme has been developed exclusively for CJR to


Ship & Boat International September/October 2008


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