VELOCITY PREDICTION PROGRAM
The aerodynamic model is embedded inside the VPP and has been fed by the different wind tunnel and aero CFD tests done in the past 10 years thanks to our involvement in the America's Cup, the Admiral's Cup 1999 and more recently the Volvo Ocean Race campaigns.
This model simulates the forces and moments of a given sail plan across a wide range of sail trims and wind velocities. Its output is then used by the VPP to quantify the required stability and balance for a given sailing condition.
The VPP [velocity prediction program] is a tool used at the very end of the analysis process where all the forces and moments tested, both aero and hydro, are put together and combined with the yacht's righting moment to output the performance of a given candidate design across the range of wind speed and angles. We have developed our own VPP software that enables for a full freedom static solution that includes leeway and rudder angles.
The VPP output [usually called “polars”] is then taken to a higher level, a racing model that simulates the performance of a candidate design on a specified race course based on historical wind and current data. Both performance prediction programs have proven remarkably accurate in the Volvo Ocean Race.