Question 39 TV03 - Towing Vessels - Western Rivers

The Correct Answer is D **Explanation for D (law enforcement vessels):** According to the Inland Navigation Rules (specifically 32 CFR Subpart C, Rule 21(b) and associated guidance or local rules, often implemented through the US Coast Guard), a flashing blue light is an identification signal used exclusively for **law enforcement vessels** operating on inland waters of the United States. This signal helps distinguish them from other vessels and indicates they are performing official duties. **Explanation for A (dredge pipelines on trestles):** Dredge pipelines are generally marked by fixed or flashing yellow lights (to indicate a preferred channel side) or white lights, depending on their location and the specific local rules or markers required by the Army Corps of Engineers or Coast Guard. They do not typically use a flashing blue light. **Explanation for B (air-cushion vessels in the non-displacement mode):** Air-cushion vessels (like hovercraft) operating in the non-displacement mode (i.e., "flying" or on cushion) are required to display an **all-around flashing yellow light** in addition to their regular navigation lights. They do not use a flashing blue light for identification. **Explanation for C (U.S. submarines):** U.S. submarines, when surfaced or partially submerged, follow specific protocols for navigation lights, which often include an amber or yellow intermittent flashing light (sometimes referred to as the "sub warning light") to indicate their presence. They do not use a flashing blue light as a standard identification signal under the Inland Rules.