Patent attributes
A navigation device is disclosed that provides navigational guidance to boats needing to cross a boundary line at a milestone event time. Port and starboard laylines and guidelines may be displayed with the boundary line using wind direction data. The port and starboard layline angles may change with the wind direction, while their lengths may represent a distance traversed by the boat tacking at the port and starboard layline angles for a target time period at a target speed. A predictor line may be displayed extending from the boat in the direction in which the boat is traveling and may have a length indicating a distance traversed by the boat at its current speed until the milestone event time. The predictor line length and color may provide feedback regarding whether the boat will cross the boundary too early or too late given its current speed and direction.