Category Archives: Astro Navigation Topics

The Polynesian Star Compass (Learning from the Polynesians)

Updated version. “Know the stars and you will always have a compass”  (The Revenant) * Nainoa Thompson tells us how that, for centuries before European sailors reached the Pacific Ocean, the South Sea Islanders accurately found their way from island … Continue reading

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Astro Navigation In A Nutshell Part Four

Part 4 – Full procedure for establishing an astronomical position line. This post brings together all of the information from parts 1, 2 and 3 of this series to demonstrate the full procedure for establishing an astronomical position line. .Links:  Astro … Continue reading

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Astro Navigation In A Nutshell Part 1

Part 1 – The Importance of Azimuth and Altitude.  The theory of astro navigation depends on the ability to solve the spherical triangle PZX in the diagram below.  The azimuth and altitude enable us to calculate the Local Hour Angle … Continue reading

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Astro Navigation In A Nutshell Part 2.

Part 2 – The Intercept Method Link:  Astro Navigation In A Nutshell Part One Suppose we are in a yacht and we measure the altitude of the Sun and find it to be 35o; what does this tell us?  All … Continue reading

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Astro Navigation in a Nutshell Part 3

Part 3 – Calculating Altitude and Azimuth at the Assumed Position by Spherical Trigonometry. Links:  Astro Navigation In A Nutshell Part One Astro Navigation In A Nutshell Part Two There are several ways of calculating the azimuth and altitude at the … Continue reading

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Short Distance Sailing And Rhumb Line Sailing

In my previous post about the meridian passage long method, I demonstrated how the ‘Short Distance Sailing Formulas’ are used to calculate a vessel’s position at meridian passage.  I have since received several questions asking how these formulas allow for … Continue reading

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Survival – The Star Compass

“Know The Stars And You Will Always Have A Compass”. In a survival situation, whether at sea or on land, the chances are you may have nothing to navigate by other than the stars in the sky. Finding the Direction … Continue reading

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The Demystified Astro Navigation Course Unit 6

UNIT 6 –  Calculating zenith distance and azimuth at assumed position. We can use sight reduction tables to calculate the zenith distance and azimuth at the assumed position or else we can use the traditional method of making the calculations … Continue reading

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The Demystified Astro Navigation Course – Unit 3 Part 1

Unit 3  Part 1 – Altitude and Azimuth     The Azimuth is similar to the bearing in that it is the angle between the observer’s meridian and the direction of the celestial body.  However, whereas bearings are measured clockwise from north … Continue reading

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Calculating the Distance Between Meridians of Longitude Along a Parallel of Latitude.

At the Equator, the distance between meridians of longitude is 60 n.m. (or 60.113 to be precise).  However, as we move north or south away from the equator, we find that the distance between them decreases as they converge towards … Continue reading

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