Investigation on Rudder Application for 470 Class Yacht Based on Mechanical Analysis

The hydrodynamic performance of the hull and appendage of the sailing boat is essential to improve the result in the sailing regatta and the rudder is an important appendage to adjust the course and balance the boat. In order to obtain the hydrodynamic characteristics of the rudder for 470 Class yacht, Reynolds-averaged Navier-Stokes Equations were used to simulate the viscous flow field of the hull and rudder for 470 Class yacht based on the computational fluid dynamics. It was indicated that the stalling angle of the rudder was 30 degrees when the displacement was 280 kg and the speed was 2 m/s to 8 m/s. With the increase of the sailing speed, the wake flow of the hull would influence the effective area and aspect ratio of the rudder. When the speed was 10 m/s, the stalling angle of the rudder was 35 degrees. Lift-drag ratio will higher when the rudder angle was 10 degrees to 25 degrees. The rudder angle was 30 degrees to 35 degrees when a larger angle turn would happen in the sailing regatta. When a boat was making a penalty turn, it could effectively save cost penalty time if the speed of the sailing was improved and the rudder angle with the larger lift coefficient was used. The results of numerical simulation was applied to analysis of the rudder steering, passing each mark and getting rid of the penalty in the sailing regatta based on the racing rules of sailing.