AMPLITUDE in Celestial Navigation |

Why do modern ship bridges, equipped with the latest electronics, still rely on observing a rising or setting Sun? Amplitude, one of the oldest, simplest, and most reliable techniques used in celestial navigation to calculate compass or gyro error
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Whether you are a maritime student preparing for your deck officer exams or a seasoned navigator standing watch, this video breaks down the exact textbook theory and practical bridge applications of amplitude
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📌 In this video, you will learn:
What is Amplitude? We define the angular distance of a celestial body east or west of the true east-west point of the horizon during theoretical rising or setting
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The Formula: How to quickly calculate amplitude using the formula: Sine Amplitude = Sine Declination ÷ Cosine Latitude
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The Battle of the Horizons: We visualize the critical difference between the mathematical Celestial (Rational) Horizon (assumed by amplitude tables) and the Visible Horizon (what you actually see from the bridge)
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The "Visual Cue" Secret: Why navigators take their bearing when the Sun's lower limb is approximately half to two-thirds of a diameter (about 21 minutes of arc) above the visible sea horizon
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When to Apply Corrections: We explain why traditional visual methods work well at low to mid-latitudes, and when you must apply Bowditch Table 23 (or 28) corrections to account for the difference between the visible and celestial horizons
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More on Amplitude - https://thedeepdraft.com/2026/01/05/amplitude-understanding-horizons-visual-cues-and-practice/