A method is disclosed that resolves a long-standing seafaring problem of how close to the wind to sail. Sailboats need a convenient way to determine the optimal heading to minimize the Tacking Time to Destination (TTD). Unlike Velocity Made Good (VMG), the method disclosed here allows route planning before the trip, predicts travel time on different points of sail, allows comparison of the optimal tacking routes, and also plots the different routes so that it is inherently obvious that a particular tacking angle is longer and more off-course but will arrive sooner because of the speed on that heading. These principles can be implemented with manual dials that define the distance and speed, to calculate the relative or actual travel time on a leg without using electronics. Software is also described that visually illustrates the current and optimal headings by calculating Tacking Time to Destination before departure.