Meridional Parts

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

NavigationMercator

Latitude (°)°

Meridional parts: 2,607.90 -

Changing the inputs requires JavaScript. The calculator above shows its default inputs and 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

In short

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

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