Is Passing a Red and White Buoy Dangerous? Maritime Rules Debunked
By Maya Lin-Takahashi
Rookie helm errors often stem from conflating safe water marks with other specialized aids. An isolated danger marker features horizontal black and red stripes with two black spheres, warning of an immediate submerged rock or wreck directly beneath it. A preferred channel marker carries horizontal green and red bands, telling the helmsman that safe passage exists on both sides but one route offers greater depth. Passing an isolated danger buoy too close can shatter a running gear, whereas a safe water mark invites approach.
| Marker Type | Color Pattern & Shape | Light Characteristics | Passing Rule |
|---|---|---|---|
| Safe Water Mark | Vertical red & white stripes; sphere/pillar | White; Morse Code "A", Isophase, Occulting | Pass either side; keep to port in fairway traffic |
| Isolated Danger | Horizontal black & red bands; two black spheres | White; Group Flashing (2) | Give wide berth; hazard lies directly below |
| Preferred Channel (Port) | Horizontal green & red bands; green can top | Green; Composite Group Flashing (2+1) | Treat as green can; keep to port entering harbor |
| Preferred Channel (Starboard) | Horizontal red & green bands; red conical top | Red; Composite Group Flashing (2+1) | Treat as red nun; keep to starboard entering harbor |
Federal guidelines established by the United States Coast Guard (USCG) and cross-referenced in NOAA nautical charts label these locations with distinct notations. On electronic and paper vector charts, a safe water mark appears as an upright magenta diamond with a circle, often accompanied by the abbreviation "RW" (red-white) and "Mo(A)" denoting the light phase.
Maya is a hardware enthusiast who tests and reviews smart home devices, smartphones, wearables, and audio gear. She focuses on practical consumer value and build quality.
