Parallel Sailing Find the distance travelled by a ship on a course of 090° T at latitude 45° N. If its longitude changed by 20°. If latitude was 60° N, find the distance. 20° = 20 * 60 = 1200′ of arc For 45° N: dep = dlong * cos lat = 1200 * cos … Continue reading Plane Parallel Mercator Sailing Formula