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Span provides sailing performance analysis for yachts in a variety of sailing conditions and produces performance polar curves to show predicted speeds.
Designers of sailing yachts who use Maxsurf can take advantage of Span to predict the performance of their designs in a variety of sailing conditions.
Using calculation methods similar to the original IMS Velocity Performance Prediction Program, Span solves the equations for lift and drag for hull and rig and finds an equilibrium velocity and angle of heel. Span's calculations operate through a variety of true wind angles and speed and calculate with both spinnaker up and spinnaker down.
Integrated into Span is a hull measuring capability which automatically measures the Maxsurf design to extract the required input measurements and parameters. Alternatively a small number of key values may be entered directly from an IMS certificate.
Output from Span is provided in both tabular and graphical format for each wind strength and direction. Results include apparent wind strength, hull velocity, Vmg, heel angle and the various lift and drag forces involved. The family of polar performance curves produced can be clicked on to find key values for any setting.