USCG Exam PracticeLatitude, longitude, and geographic coordinates
A mariner measures distance on a Mercator chart using dividers. Against which scale must the measurement be made?
- A. The longitude scale at the top or bottom of the chart
- ✓ The latitude scale at the vessel's working latitudeCorrect
- C. The latitude scale at the midpoint between the equator and the destination
- D. The longitude scale nearest to the vessel's meridian
Why B is correct
Bowditch Ch. 4 §405 and §406 both specify that distance is measured on the latitude scale at the vessel's own (working) latitude, because one minute of latitude equals one nautical mile and meridian length varies with latitude on a Mercator chart.