Advance an initial position by a course and speed for a given elapsed time - the basic DR calculation.
Formula
$$ d\text{Lat} = D \cdot \cos C, \quad \text{Dep} = D \cdot \sin C, \quad d\text{Lon} = \tfrac{\text{Dep}}{\cos L_m} $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $C$ | True course | °T | course order |
| $D$ | Distance | nm | SOG × time |
| $L_m$ | Mid-latitude | ° | averaging |
| $Dep$ | Departure (east-west distance in nm) | nm | derived |
Sources
- Bowditch - American Practical Navigator.