What to know for Radar Plotting and CPA
Use repeated radar observations to judge whether a target will pass clear or become a collision risk.
Relative motion, closest point of approach, target trails, and manual plotting discipline. This module is mapped to the published course boundary for Marine Radar Revision and written as an independent revision aid, not official training material.
Key Points
- A steady relative bearing with decreasing range is dangerous
- CPA needs time-separated observations
- Target trails show history, not guaranteed future
- Action must still comply with COLREGs
Last reviewed: 6 July 2026 by Compass Revision curriculum review
Source notes
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