NavCalc is a simple navigation calculator. Given a desired heading, boat speed, and the set and drift of current, NavCalc will display the Course to Steer (CtS) and Speed over Ground (SoG) that will be achieved on that course given the current.

NavCalc draws a neat little picture of the heading, current vector, and course to steer on a 360º compass rose which includes both degrees True and Magnetic (if you enter a Magnetic Variation). NavCalc also allows you to enter degrees of leeway and wind direction, and will take leeway into account when calculating the CtS.

NavCalc will dynamically update the drawing as you change any of the parameters (heading, boat speed, current set or drift, variation).

NavCalc can be used to solve navigation problems like the ones you might find on the tests for Coastal Navigation courses from US Sailing or ASA. It’s also useful for building intuition about how current affects your boat’s course and speed over ground (or velocity made good) since it updates dynamically as you change any parameter.