Radar Observer · Limitations — Blind and Shadow Sectors
Blind and shadow sectors on a vessel's radar are caused by:
- AMasts, funnels, or other obstructions blocking or weakening the beam in certain relative directions✓ Correct
- BRain in the atmosphere
- CA mis-set heading marker
- DLow gain only
Explanation
Obstructions near the scanner (masts, kingposts, funnels) block (blind) or partially shadow the beam in fixed relative bearings, so targets there are missed or weakened. These sectors should be known, minimized in scanner siting, and posted at the radar; the ship may need to yaw to clear a blind sector.
Authority: Bowditch (Pub. No. 9); IMO Performance Standards
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