Mariner's Astrolabe

Mariner's Astrolabe

The most popular western navigational instrument for centuries, the astrolabe allowed mariners to track their latitude as the explored the world. Notoriously difficult and inaccurate, Columbus reportedly hurled his overboard in the Sargasso Sea before making landfall half-a-world off course.

To use, sight Polaris through the pinholes in the alidade while holding the instrument level with the horizon and read the angle to calculate latitude. Astrolabes can also be use for dead reckoning by holding the instrument horizontally, aligning the top to North, and taking a bearing off you target.

Astolabes are a great tool for introducing students to celestial navigation and teaching trigonometry.

For inspiration and instruction, I use the following books: Latitude Hooks and Azimuth Rings: How to Build and Use 18 Traditional Navigational Tools, The Lo-Tech Navigator, and Emergency Navigation: Improvised and No-Instrument Methods for the Prudent Mariner.

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