Meridional Parts

Meridional parts at a given latitude - the core quantity behind Mercator sailing and chart construction.

NavigationMercator

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This calculator requires JavaScript to compute its result. The formula, symbols, and regulatory sources are shown in the Formula section below.

Formula, assumptions, and limits

M = 7915.704 \cdot \log_{10}\left[\tan\left(45 + \tfrac{\varphi}{2}\right)\right] - 23.013 \cdot \sin\varphi

Symbol	Meaning	Unit
$φ$	Latitude	°
$M$	Meridional parts at latitude φ

Source: Bowditch - Meridional parts; Norie's Tables 41

Meridional parts at a given latitude - the core quantity behind Mercator sailing and chart construction.