Procedure for production of scaled ship models for towing tank testing
Ship owners traditionally use the results of towing tank tests to evaluate ship performance. Scaled ship models must be created for this purpose. According to ITTC instructions the models dimensions must not exceed 1mm tolerance in all directions. The accuracy of the design and manufacture process is crucial to obtain the desired result. In other ways, the reliability of the towing tank tests may be questionable. In this respect, the Laboratory for Ship and Marine Hydrodynamics (LSMH) of NTUA propose a design method to ensure the reliability of the procedure. The Laboratory has recently revised a two and half axis CNC machine for producing scaled ship models, based on a traditional twin spindle 2% axis hand driven ship model milling machine. This machine consists of four servo motors in conjunction with Mach3 controller that cooperates with CAD/CAM software. In our case, the commercial 3D software Rhinoceros 5 was used. The process used to build the model from the ship’s construction plans will be presented in detail. Areas were special attention is needed will be remarked.