Chart Navigation & Plotting · Dead Reckoning — When to Plot
Standard practice is to plot a new DR position at every course change, every speed change, every fix or LOP, and:
- AOnly at noon
- BOnly once per watch
- CEvery hour on the hour✓ Correct
- DOnly when entering port
Explanation
DR positions are established at each course change, speed change, fix or single LOP, and every hour on the hour. Disciplined DR provides a continuous estimate of position between fixes and a check on the fixes themselves.
Authority: Bowditch (Pub. No. 9), Dead Reckoning
Practice the full Chart Navigation & Plotting bank
Free spaced-repetition quizzing across 2550 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?