Hydrodynamic Forces Acting on a Ship in Oblique Towing

The objective of this paper is to afford a more rational method of calculation for hydrodynamic forces on a ship in manoeuvering motion. Applying the slender body theory and extending the Barche's method to a ship form associated with free vortex layers which represent 3-dimensional separation vortices, the problem can be reduced to some 2-dimensional problems. More precise hull form or ship condition can then be taken into consideration for hydrodynamic force calculation. The author calculates by this method normal force coefficient CN and moment coefficient Cm_??_ for various ship models, and compares the calculated results with tank test results. These comparisons affirm the validity of this method. He also measures the pressure distribution on a ship hull in steady oblique towing, the results of which show a good agreement with those of potential flow calculation except in small region located at lee side and aft part of the ship.