Rhumb-line (constant-course) distance and true bearing between two positions using Mercator meridional parts.
Formula
$$ \tan C = \frac{\text{DLo}}{\text{DMP}}, \quad D = \text{DLat} \cdot \sec C $$Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $DLo$ | Difference in longitude | min of arc | derived |
| $DMP$ | Difference in meridional parts | - | Norie’s tables |
| $DLat$ | Difference in latitude | min of arc | derived |
| $C$ | Rhumb-line course | ° true | result |
| $D$ | Rhumb-line distance | nm | result |
Sources
- Bowditch Ch.4.
- Norie’s Nautical Tables.