Question 55

The Correct Answer is C ### Explanation for Correct Answer (C - Safe water) Under the U.S. Aids to Navigation (ATON) System, a buoy that indicates "Safe Water" is known as a **Safe Water Buoy** (or Fairway Buoy). These buoys are used to mark the centerline of a channel or to indicate that navigable water surrounds the mark. Key characteristics of a Safe Water Buoy are: 1. **Color:** Red and white vertical stripes. 2. **Light (if present):** White light. 3. **Rhythm:** Morse Code 'A' (•–) or long flash (e.g., 6 seconds). 4. **Topmark (if present):** A single **red spherical topmark**. Therefore, a lighted buoy with a spherical topmark marks safe water. ### Explanation for Incorrect Options **A) The port side of the channel:** The port (left) side of the channel when proceeding from seaward (entering harbor) is marked by **green** lateral buoys (can buoys) or lighted buoys with a square or cylinder topmark. These buoys use an identifying shape, not a spherical topmark. **B) A hazard to navigation:** Hazards, such as isolated dangers like wrecks or submerged rocks, are marked by **Isolated Danger Buoys**. These buoys are colored black and red horizontally striped, and their distinctive topmark consists of **two black spheres**, one above the other. A single sphere is not used for hazards. **D) The position of underwater cables:** Buoys marking specific features like cables, pipelines, or military exercise zones are generally categorized as **Special Marks**. Special Marks are **yellow** and, if they carry a topmark, it is typically a single **yellow 'X'** shape, not a spherical topmark.