Page 20: of Maritime Reporter Magazine (October 2016)

EYE ON DESIGN: CAD/CAM

Geometry for Propeller Replacement & Repair with HydroComp PropCad

DONALD MACPHERSON he repair of large commercial many of these projects are for the repair happens. It became clear to me that we Feature Extraction for propellers is more than beating or replacement of existing propellers. needed a solution that would be ef? cient Propeller Repair

Ta blade back into shape. It re- and effective to analyze a propeller de- Argonaut is using the advanced manu- quires reference geometry as the target Replacement Propellers sign and identify possible design-related facturing features in PropCad Premium objective for the repair, as well as way “It is not uncommon that a customer issues. That solution was HydroComp’s to repair propellers. Mr. Doerr explains, to document the inspection and compli- requires a replacement for a propel- PropCad software.” HydroComp’s “In repair, propellers come to the facility ance for the repair. In some cases, exist- ler based on a drawing which could be PropCad is industry-standard software often with no drawing or design data. To ing drawings are available. Other times, 30+ years old”, comments Darryl Do- dedicated to the geometric modeling of repair a propeller to Class or to ISO-484 the geometric features must be extracted err, Managing Director of Argonaut. “A marine propellers. PropCad provides au- requirements, design values are needed. from the propeller itself. Virginia-based few years ago we had a propeller project tomatic preparation of CAD/CAM data, Without a drawing, we must fully in- company Argonaut Enterprises VB LLC based on such a drawing. During that 2D design drawings, 3D offsets, and spect each propeller to extract key de- focuses on the documentation, repair, time we did not know that there were de- thickness classi? cation reports. The lat- sign data to determine design intent and and manufacture of marine propellers. sign errors in the drawing that dramati- est additions to HydroComp’s PropCad create a repair drawing before repairs

They can design and deliver propellers cally in? uenced the ? nal result. It is un- software supplement the typical propel- can be made. PropCad is instrumental in from as small as 24 inches (0.6 m) to as fortunate that it takes a failure to identify ler design tasks with support for manu- nearly every project to reproduce a de- large as 26 feet (7.9 m) diameter, and a problem, but often that is exactly what facture and inspection. sign model and repair drawing.”

PropCad can interpret existing propel-

Figure 1: The main interface of HydroComp PropCad 2016.

lers, patterns, and scan reports in order to support legacy designs. The Scan

Converter utility in PropCad Premium is used to extract propeller parameters such as pitch, chord, skew, rake, and thickness using 3D data points collected from a physical propeller.

Scan Converter processes the data and recreates the propeller blade by extract- ing individual sections from the geom- etry and deriving the geometric distri- butions. Once the design is in PropCad, additional documentation such as 2D drawings, pitch inspection reports, and 3D offsets can be easily generated for customers, clients, and record keeping.

Inspection Documentation for Repair

The proper inspection of marine pro- pellers ensures the manufactured prod- uct meets the thickness and pitch speci- ? ed by the design. Traditionally, the offset positions are manually laid onto the blade surface and checked against the published offsets for the propeller. To improve this process, PropCad Premi- um offers a powerful tool for propeller builders and manufacturers – Inspection

Maps. These maps provide guidance for propeller craftsman and foundry work- 20 Maritime Reporter & Engineering News • OCTOBER 2016

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