Describes off shore navigation, safe conduct of a ship across the open sea where in general bearings of objects on land cannot be obtained except by means of radio waves. First chapters are mainly concerning distances, course, tracks and charts, then various methods of obtaining position lines and positions form astronomical observations are explained including a rapid method in the last chapter. Also contains an outline of meteorology and weather forecasting.
Author=Ministry of Defence
Book Condtion=Ex public library book.however contents excellentm with a very good dust jacket.