Righting Moment - Sideforce calculation
Righting Moment is the rotation force that keeps a yacht from heeling further. It acts against Heeling Moment due to the sail and daggerboard forces. When RM = HM heel angle is constant. The distance between the centre of sail forces and centre of daggerboard forces is called Heeling Arm HM divided by HA equals the Sideforce produced by the sails and wind, which is exactly reacted in the water by a combination of daggerboard area, leeway angle and boatspeed. An important point is that the HM can't be greater than RM. To increase Sideforce, the Heeling Arm must be reduced by twisting and/or flattening the top of the sails. Here is a simple calculator for RM of a dinghy that is being sailed upright. Enter boat, crew, sail dimensions and calculate the RM and Sideforce. Enter boatspeed, TWS and TWA and it estimates drag forces for friction, lift-induced drag, windage. Righting Moment - Sideforce (Read the Manual page for instructions) Currently the workbook