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www.sea-technology.com August 2016 / st 33 A rgonaut Enterprises VB LLC is a Virginia-based company focused primarily on marine propulsion systems design, part of which is the documentation, repair and manufac- ture of propellers. They can design and deliver propellers from as small as 24 in. (0.6 m) to as large as 26 ft. (7.9 m) in diameter. Darryl Doerr, managing director of Argonaut, told us about his use of HydroComp PropCad software, and particularly about the assistance of HydroComp staff in de- veloping advanced inspection and documentation features for the new Premium Edition of PropCad. "It is not uncommon that a customer requires a propeller replacement based on a propeller drawing done by a naval architect or shipyard when a ship class was originally built and which could be 30-plus years old," he noted. "A few years ago, we had a propeller project based on a customer's drawing. During that time we did not know that there were design errors in the drawing that dramatically influenced the final result. It is unfortunate that it takes a failure to iden- tify a problem, but often that is exactly what happens. It became clear to me that we needed a solution that would be efficient and effective to analyze a propeller design and identify possible design-related issues. That solution was HydroComp's PropCad software." PropCad PropCad is software for geometric modeling of marine propellers for design and manufacture. It pro- vides automatic preparation of CAD/CAM data, 2D design drawings, 3D offsets and thickness classification reports. The latest additions to HydroComp's PropCad software supplement the typical propeller design tasks with support for manufacture and inspection. Propellers come in many sizes and styles for different applications. As such, the design and manufacture of a marine propeller can be a complex task, and HydroComp focuses on solu- tions to make propeller design easier, faster and more reliable. PropCad is HydroComp's tool serving design- for-manufacture, whereas other products, such as Hydro- Comp's PropElements, are design-for-performance products. Design-for-manufacture relates to how the specified design parameters are integrated into a propeller's blade geometry. Traditionally, propeller geometry was largely cre- ated by hand. Skilled craftsmen and foundry workers manu- ally measured wooden patterns and laid up the sand-molds for casting with painstaking care. The rough castings were hand-finished and inspected using fitted gages. Today, pro- peller geometry is developed using computer models, and PropCad is a design-for-manufacture modeling tool run by over 160 software users in 40 countries. Support for Design At the heart of PropCad is a library of traditional propeller designs that allows users to rapidly develop geometries. The library has over 10 different propeller series, and PropCad users' can mix and match characteristics from different de- signs to quickly create their own unique propeller recipe. The design is controlled by individual parameters, such as nominal pitch and BAR. The parameters are matched us- ing radial shape distributions. For example, the BAR target is met by scaling the outline of the propeller, which is a distribution of chord lengths (width of the blade sections). The radial shape distributions can come from many sourc- Inspection, Documentation Of Marine Propellers PropCad Models Propeller Geometry for Design and Manufacture By Adam Kaplan The main interface of HydroComp PropCad 2016.