Question 4 AB01 - Able Seafarer

The Correct Answer is A **Explanation for Option A (Morse (A) being correct):** In the United States Aids to Navigation System (USATONS), buoys marked with red and white vertical stripes are designated as **Safe Water Marks**. These marks indicate that there is navigable water all around the buoy (e.g., they might mark a channel centerline or mid-channel). By international convention and U.S. regulations (specifically outlined in the U.S. Coast Guard's light lists and navigation rules), Safe Water Marks, if lighted, are required to exhibit a **Morse (A) light characteristic**. The Morse (A) characteristic is a long flash preceded by a short flash (dot-dash), which is unique and instantly identifies the mark as a Safe Water Mark. **Explanation for why the other options are incorrect:** * **B) Interrupted quick flashing:** This characteristic is reserved for **Isolated Danger Marks** (black and red horizontal stripes), which mark a danger of limited extent with navigable water all around it. * **C) Group occulting:** While group occulting characteristics (where the light is off for a specified number of intervals) are used on some navigational aids, they are not the specified characteristic for Safe Water Marks. Steady, periodic, or composite group flashing characteristics (like Group Flashing (2) or (3)) are typically used for lateral marks (red or green buoys) to identify specific channel sections. * **D) Quick flashing:** Quick flashing (QF) or Very Quick Flashing (VQF) lights are typically used for **Lateral Marks** (red or green buoys) that indicate the side of the channel, particularly where special attention is required, such as at turning points or junctions. They are not used for Safe Water Marks.