VPP, Velocity Prediction Program

A Velocity Prediction Program computes a yacht’s steady-state boat speed at every combination of true wind speed and angle by balancing the driving force from the sails against the hull’s resistance and the righting moment from ballast and crew. The output is the boat’s polar diagram, the speed it can hold on each point of sail. VPPs underpin the ORC rating system and feed onboard tactical software that tells a navigator the optimum heading for best velocity made good toward the next mark.