Dead-reckoning position error growth from course, speed, leeway and current errors over elapsed time - the uncertainty budget for DR legs.
Formula
$$ \sigma_{DR} = \sqrt{(D \sin \sigma_C)^2 + (D \sigma_S)^2} $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $D$ | Distance on DR | nm | speed × time |
| $\sigma_C, \sigma_S$ | Course, speed errors | deg, % | gyro, log accuracy |
Sources
- Bowditch Pub.9 Ch.23.