A Comparative of Component Resistance and Form Factor of Four Patrol Boat

Abstract

The most common type of patrol boats is semi-displacement ships, the design of a 60 meters patrol boat has been built by several shipyards for the Indonesian Navy. Four patrol boats model were retested at the Indonesian Hydrodynamic Laboratory for a resistance test. Based on resistance test, the total resistance components of the model were decomposed into the individual resistance components. The scale ratio effects and form factor were investigated. This study was undertaken to determine the form factor using Prohaska method. The frictional resistance coefficient of the model is calculated based on ITTC correlation line proposed by ITTC 57 and the residual resistance coefficient is derived for each model test. Result of this study show L/B ratio of model ship gets larger, on otherwise the value of the form factor k is smaller. Frictional resistance coefficient (C F) becomes smaller when Reynolds number becomes greater. The residual resistance coefficients (C R) of the model decrease while the size of the model ship increases. this study reveals the relationship between the changes in frictional resistance coefficient (C F) and residual resistance coefficient (C R) caused by the scale ratio.