Chart Navigation & Plotting · Sailings — Plane Sailing Course and Distance
Between two nearby points you have a difference of latitude of 30' N and a departure of 40' E. What is the course and distance by plane sailing?
- A045°T, 50 NM
- B037°T, 50 NM
- C053°T, 70 NM
- D053°T, 50 NM✓ Correct
Explanation
Course = arctan(departure ÷ dLat) = arctan(40 ÷ 30) = arctan(1.333) = 53.1°, i.e., N53°E = 053°T. Distance = √(dLat² + departure²) = √(900 + 1600) = √2500 = 50 NM (the classic 3-4-5 triangle).
Authority: Bowditch (Pub. No. 9), Plane Sailing
Practice the full Chart Navigation & Plotting bank
Free spaced-repetition quizzing across 2190 USCG exam questions — it schedules your reviews so the ones you miss come back until they stick.
Related Chart Navigation & Plotting questions
- Chart Basics
On a Mercator chart, one nautical mile is measured using the:
- Chart Basics
The principal advantage of the Mercator projection for navigation is that:
- Chart Basics
Charted depths (soundings) on a U.S. chart are referenced to which tidal datum?
- Chart Basics
Vertical clearances of bridges and overhead cables on a U.S. chart are normally referenced to:
- Distance, Speed & Time
A vessel makes good 12 knots. How far does it travel in 20 minutes?
- Distance, Speed & Time
A vessel covers 9 nautical miles in 45 minutes. What is its speed?