عباس دشتی منش

Determination of forces acting on planing hulls in maneuvering has been turned into an interesting problem during the last decade. Different methods, based on mathematical or empirical approaches, are elicited to compute hydrodynamic forces and moments acting on the boat in different simplified conditions, such as steady yawed or heeled conditions.Modeling of different conditions and combining them with each other may lead to initiate a final simulation model for 6DOF motion of planing boats in calm water. These simple modeling approaches, in other words, can be considered as basics of a final 6DOF model. The current article address hydrodynamic modeling of yawed motion for hard-chine planing boats in calm water. The current research paper is primarily focused on the determination of horizontal force and yaw moment acting on the boat as it moves forward in a steady yawed condition. The derivation approach is based on mathematical formulation of 2D1T theory and added mass variation in longitudinal direction. Virtual mass of a wedge in horizontal direction is analytically found and then the final force and moments are computed using extension of sectional forces, acted on wedge section of the boat, over entire wetted length of the vessel. The precision of the proposed model is verified by comparing the computational values against previous experimental data. An improvement for the model has been considered to conquer some of the drawbacks reported by previous researchers. The comparison exhibits an improvement of the model; the increase in added mass which was previously discussed by previous researchers can be seen. Also, it is observed that in the case that the wetted length of the boat is small, the transom reduction works well and leads to an accurate prediction of sway force. Finally, it is viewed that the computed yaw moments are in a fair agreement with previous experimental data.