Radar Observer · Plotting — Interval
When plotting a contact manually, taking ranges and bearings at regular timed intervals (e.g., every 3 or 6 minutes) is important because it:
- ASaves electricity
- BAllows the relative motion and therefore CPA/TCPA to be calculated accurately✓ Correct
- CReduces sea clutter
- DIs required to tune the radar
Explanation
Rule 7 requires proper use of radar including systematic observation of detected objects. Evenly timed plots establish the relative-motion line and the rates needed to determine if risk of collision exists. Scanty information must not be acted on.
Authority: 72 COLREGS Rule 7 / Radar Plotting
Practice the full Radar Observer 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 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: