Performance Prediction of the Mk II Navy 44 Sail Training Craft with respect to Tank Testing, Velocity Prediction Programs, and Computational Fluid Dynamics

Abstract

Abstract : The powering requirement of a ship is one of the most important aspects of naval architecture. Traditionally, ships have been tested for hull resistance using hydrodynamic tank testing. Tank testing evaluates models of ships by measuring their resistance in a tow tank. This has proved to be useful and accurate, but is very time consuming, expensive, and has inherent scaling errors. Because of these reasons, today many vessels are sold on the market without any model testing. Another set of design tools is parametric predictions. Parametric predictions contain acquired data for a specific family of hull forms and use key hull parameters to evaluate a particular design. Parametric predictions run quickly, but cannot be used to evaluate any hull outside of the limits of previously tested hulls. Computational Fluid Dynamics (CFD) codes are a much newer method of determining the powering requirement for ships. CFD uses numerical modeling to simulate the forces which act on the ship. Unlimited testing takes a fraction of the time and effort as compared to tank testing. However, it is not yet wholly proven in its accuracy. An investigation has been made using tank testing and CFD to predict the new David Pedrick Mk II Navy 44 Sail Training Crafts (STC) performance, The performance prediction process proved most accurate when using tank data to aid the CFD calculations. Using this combined method along with an aerodynamic calculation for the Mk II Navy 44 STC, a Velocity Prediction Program (VPP) was constructed. Finally, the new VPP as well as previous parametric VPPs were used to predict a full set of performance figures. These tools were also used to improve the rudder design of the Mk II Navy 44 STC.