Traditional astro navigation methods rely on the use of lengthy sight reduction tables to calculate position. The aim of this volume is to provide ocean-going sailors with a speedy and efficient method of fixing their position at sea using pocket computers. Assuming no prior knowledge of either computers or astro navigation, the author uses fundamental BASIC commands common to all pocket computers. He explains how to adjust the programs for additional use on personal computers in the home, and how to adapt the programs for pocket calculators in the event of loss of compass or sextant at sea. All of the programs used have been written and tested afloat.