The app includes various ship-board activities done daily usually. It includes ETA calculation, True wind speed calculation and celestial calculations which includes all 58 navigational stars, all 4 planets, sun and moon and their ephemerides. The accuracy has been compared with the nautical almanac of 2012 and US naval observatory website.In general it can calculate sights, true azimuths,hour angles (siderial,local and greenwich), declination and altitudes of all navigational stars,planets,sun and moon.It supports the 3 most widely used navigational methods--intercept,long by chron and lat by mer alt.It can also calculate rise/set and transit times for moon and sun.And finally calculates true wind speed and direction, Estimated Times of arrival at various speeds,displays the phone's compass heading and the GPS position.Use at your own risk ********P.S. Before using the fix calc tab set up the sight parameters first by clicking on menu-settings and then set up temperature,pressure,height of eye.Read help carefully .