Description:TVMDC Sailing & Marine Navigation Calculator is a specialized iPhone app crafted for sailors and navigators who want to sharpen navigation skills using nautical charts. It performs instantaneous conversions between true, magnetic, and compass bearings using TVMDC correction, calculates set and drift from two known fixes, and computes the correct course to steer (CTS) that accounts for magnetic variation, deviation, and water currents. Its strength lies in delivering precise navigational calculations with minimal setup, accompanied by a visual sailing triangle that helps users understand the geometry. Ideal for sailing students, recreational boaters, and navigation trainees who value reliability, clarity, and hands-on practice.
How to use:Launch the app and enter your chart’s magnetic variation, its annual change rate, the chart year, and your vessel’s compass deviation
Input a bearing (true, magnetic or compass) and the app instantly shows the corresponding values in the other systems
Enter two known fixes with timestamps along with your heading and speed to calculate set and drift and view the graphical sailing triangle
Specify your destination and current speed and the app computes the optimal course to steer factoring in TVMDC corrections and set and drift errors
Review the results to understand the bearing conversion, set & drift triangle, and recommended course to steer for accurate navigation