Navigation

This is the third in a series of articles on celestial navigation. It focuses on the use of the sextant. Specifically, it covers how to: Taking a sextant reading is the most practical part of celestial navigation. It is also the most romanticised, the most frequently depicted in images and...

This text is the fourth in the series on astronomical navigation. It deals with the corrections to be made to observations taken with a sextant. The text on how to take observations with a sextant should be read first. For reasons that will be explained later, the observed altitude of...

This text contains sight reduction exercisesusing the Ho 249 reduction tables. Beforehand, you should read the text on sextant observation reduction or, more generally, the series of texts on celestial navigation. Exercise 1 Your estimated position is at 50° 18.7’N / 058° 23.89’W at 1825 UTC-3.5. The observed altitude of...

Here is a series of five reduction exercises based on sextant observations, using spherical trigonometry. To understand how to complete these exercises, you will need to have read the text on reducing sextant observations or, more generally, the series of texts on celestial navigation. Exercise 1 Your estimated position is...

This text is the sixth in a series on celestial navigation. It focuses on the method for converting sextant readings into a position line, i.e. a reduction of sextant observations. The text explaining how to find the GP of a celestial body should be read beforehand. The reduction is the...

In developing a theory of celestial navigation, we have seen that a ship’s position is determined using circles of position centred on the GP of a celestial body. This fifth article in the series on celestial navigation shows how to find the GP of any celestial body. This is an...

This is the second in a series of articles on celestial navigation. It sets out the theory needed to understand how the technique works. The focus is on understanding, rather than calculation: we’re looking at the big picture. No calculations! The idea is to understand the simplifications required to arrive...

This is the first in a series of articles on celestial navigation. It covers the tools and documents required for celestial navigation, namely: You don’t need anything else. A basic scientific calculator with trigonometric functions (sin, cos, tan, etc.) costs around $20. A ruler costs next to nothing, but it...