A spinnaker is a special type of sail that's designed specifically for sailing off the wind from a reaching course to a downwind, for example with the wind 90°–180° off the bow. The spinnaker fills with wind and balloons out in front of the boat when it's deployed, called flying. It is constructed of very lightweight, usually nylon, fabric, and is often brightly colored. It may be optimised for a particular range of wind angles, as either a reaching or a running spinnaker,… (More on Spinnaker)