Abstract: Systems, methods and computer program products for sensor-based sailboat sails, including a device to detect whether a flow on a sail is attached or separated including a flow separation sensor; a device using data from the separation sensor to trim the sail; a wind history device for storing a history of wind conditions on the sail; a UV-exposure sensor for measuring UV-exposure on the sail; an acceleration sensor to measure an attitude of the sail; a stress or strain sensor to measure stretch and loading of the sail; an energy supply to provide energy to the sensors; and a data display to show data from the sensors to a user.