Radar Observer · Plotting — Closing Speed Overtaking
You are overtaking another vessel on the same course; you make 18 knots and she makes 12 knots. The rate of closing is:
- A30 knots
- B6 knots✓ Correct
- C12 knots
- D216 knots
Explanation
When both vessels steer the same course, the closing rate is the difference of speeds: 18 − 12 = 6 knots. The low relative speed in an overtaking situation gives more time, but you remain the give-way vessel under Rule 13.
Authority: Bowditch (Pub. No. 9), Radar Plotting
Practice the full Radar Observer 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 Radar Observer questions
- Display — Motion
On a relative-motion radar display, your own ship is:
- Collision Avoidance — CPA
The closest point of approach (CPA) of a radar target is:
- Collision Avoidance — TCPA
TCPA on a radar/ARPA readout represents the:
- Controls — EBL
The electronic bearing line (EBL) on a radar is used to:
- Controls — VRM
The variable range marker (VRM) on a radar measures:
- Controls — Clutter
The anti-clutter sea (STC / sensitivity-time control) is adjusted to: