Navigation Exercise 1

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To work out your Latitude, you will need to know

• Days from Equinox (negative during Northern Winter)

and one of:

• The Sun's Elevation at Noon
• Hours of Sunlight
• Bearing at Dawn

Calculate Seasonal Tilt, using either the Chapter Five charts, or the advanced formulae.

Latitude from Elevation at Noon

• Latitude = Seasonal Tilt + (90 - Sun Elevation at Noon)

Note This method is covered in more detail in Chapter Seven

Latitude from Hours of Sunlight

• Latitude = ArcTan( Sine((SunlightHours-12)*7.5) / Tan(SeasonalTilt) )

Note This method is wildly sensitive to measurement errors during the middle months of Spring and Autumn, and is not great during the rest of these seasons.

Latitude from Bearing at Dawn

• Latitude = ArcCosine(-Sine(Seasonal Tilt)/Cosine(Bearing at Dawn))

Note This method is wildly sensitive to measurement errors except near the Arctic circles in local Summer.