Comments by Germán Frers: This diagram show average speed, not top speeds, in various wind conditions and sailing angles. They can be used as a guide to sail the boat at best using the apparent angles upwind and downwind which yield the best VMG (speed made good). Red lines are without spinnaker, blue ones with. Figures on the line is true wind speed in knots, figures at the left, lower and top end of the diagram is boat speed in knots.