Nautical Almanac

A comprehensive publication containing astronomical data and navigational information essential for maritime navigation.

A Nautical Almanac is an indispensable resource for mariners, providing the celestial data required for accurate navigation at sea. Published annually, it contains detailed information about the positions of celestial bodies, such as the Sun, Moon, planets, and selected stars, at specific times throughout the year. This data enables navigators to perform celestial navigation, a traditional method of determining a vessel’s position by observing the angles between celestial objects and the horizon using a sextant. 

The almanac also includes tables for calculating the altitude and azimuth of celestial bodies, as well as information on phenomena such as sunrise, sunset, moonrise, and moonset. Additionally, it provides details on tidal data, timekeeping, and other navigational aids. In the UK, the Nautical Almanac is jointly produced by His Majesty’s Nautical Almanac Office (HMNAO) and the United States Naval Observatory (USNO), ensuring consistency and reliability in the data provided.

While modern electronic navigation systems, such as GPS, have become the primary tools for maritime navigation, the Nautical Almanac remains a critical backup resource. It is particularly valued for its independence from electronic systems, making it a reliable tool in situations where technology fails or is unavailable. Its continued use underscores the enduring importance of traditional navigation skills in the maritime world.