Development of Free-running Radio Control Model of Small Boat with Outboard Engine and Validation of Low-Speed Maneuvering Motion Simulation

In this study, a free-running model with an outboard motor is development and the results of free-running model tests are compared with maneuvering motion simulations using data tables of fluid forces measured in full captive model tests to verify the validity of the proposed measurement range and number of measurement conditions. It is found that differences in draft between free-running test and captive model tests can cause the fluid forces acting on the hull to become relatively larger than the thrust, resulting in an underestimation of simulated ship speed. However, by correcting for displacement effects the simulation results more closely matched the experimental data. It is also found that minor variations in drift angle significantly influence discrepancies between free-running test and simulation results, including the turning radius, acceleration behavior, and heading changes after steering. Furthermore, reducing the number of test conditions for measuring thrust and rudder forces led to discrepancies between the simulated and experimentally observed ship speed and drift angle under very low-speed forward or reverse-propeller conditions.