Spinnaker trimmed for broad reach showing transition from boundary layer to detached flow where vortex shedding commences. "VA" is the apparent wind. Based on source: TWO-DIMENSIONAL CFD-BASED PARAMETRIC ANALYSIS OF DOWN- WIND SAIL DESIGNS S. J. Collie , University of Auckland, NZ, P. S. Jackson, University of Auckland, NZ, M. Gerritsen, Stanford University, USA, and J.B. Fallow, North Sails New Zealand Ltd., NZ