🌐 Meridional Parts Calculator
Calculate Meridional Parts (MP) for Mercator Sailing, determine Difference (DMP), or perform reverse lookups (MP to Latitude) with high precision.
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Meridional Parts Calculator Modes
Supports: DD, DMS, DM (e.g. 45°30'15")
About Meridional Parts
Meridional Parts (MP) represent the distance in minutes of longitude from the equator to a given latitude on a Mercator chart. This calculator matches values in Norie's Nautical Tables, used in maritime licensing exams worldwide.
Formula (Sphere):
MP = 7915.7045 × log₁₀(tan(45° + Lat/2))
Essential for chart work, Mercator sailing problems, and constructing custom navigation tables.
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How to Use the Meridional Parts Calculator
For Students:
- Solving Mercator sailing problems in maritime exams
- Verifying Norie's Tables lookups for accuracy
- Understanding chart distortion at high latitudes
- Generating practice problems for navigation courses
For Professionals:
- Quick course calculations without physical tables
- Generating custom MP tables for training materials
- Reverse engineering chart projections
- Validating electronic chart system calculations
Why Use Our Meridional Parts Calculator?
- ✓Lightweight and accurate - 2 decimal places and lightning fast calculations
- ✓Bidirectional calculations - Convert Lat→MP or MP→Lat instantly
- ✓Batch processing - Generate entire MP tables in seconds
- ✓WGS84 Spheroid accuracy - Real-world ellipsoid calculations, not just perfect sphere
- ✓Free & ad-free - No login required, unlimited calculations
- ✓Mobile-friendly - Calculate MP values on deck or in the classroom
Example: Mercator Sailing Problem
Problem:
A vessel sails from 30°N to 50°N. Calculate the DMP (Difference in Meridional Parts).
Solution:
- Find MP at 30°N = 1876.86
- Find MP at 50°N = 3456.82
- Since both latitudes are in the same hemisphere (N), subtract:
DMP = 3456.82 - 1876.86 = 1,579.96 minutes
💡 Use the "DMP Calculator" tab above to verify this calculation instantly!