Asymmetrical Spinnakers are a special class of sail that fills in the performance gap between genoas and spinnakers on a boat equipped for a standard spinnaker. On a "Sport" or "Sprit" boat, they reaching and downwind sails. a leech and luff just like a genoa does and the luff is substantially longer than the leech. The longer luff maximizes the driving force of the sail. The higher clew allows the leech to open, reducing drag Besides being dimensionally asymmetric, these sails are asym- metrically shaped also meaning that they are designed and built with powerful luffs and flat leeches. Their draft is built in by shaping the panels in much the same fashion as is used in genoas. necessarily a single sail type any more than genoas are. There is potentially a greater variety of shapes, sizes and cloth weights in asymmetrical spinnakers than in genoas or conventional chutes. Close reaching asymmetries have a designed to fly flat and close to the boat like a genoa. For broad reaching, they are designed with wider girths and wider head angles and fly further from the boat like

This graph also shows some other i. There is a trade-off between pointing and power. Flatter sails can be carried at narrower angles but don't develop as much driving power 2. A sail is at its best when used at an angle about 10 to 30 degrees wider than the closest angle the sail can achieve. At angles wider than this, the performance gradually falls off. At closer angles, the performance 3. Flatter asymmetries have a sharper peak in their performance curve. Editors Note A Staysail can slightly increase the driving force at wider wind angles. OPTIMUM POWER RANGES Analysis of the Forward Driving...