Question 30
ONC06BOTH INTERNATIONAL & INLAND You see ONLY the light shown in illustration D080RR below. Which type of vessel are you observing?

AI Explanation
The Correct Answer is C
**Why option C ("sailing vessel") is correct:**
Illustration D080RR shows a combination of navigation lights: a **red over green** all-round light configuration. According to both the International Regulations for Preventing Collisions at Sea (COLREGs) Rule 25 and the U.S. Inland Rules, a power-driven vessel underway must show sidelights and a sternlight, and if applicable, masthead lights. However, a **sailing vessel** underway may show the standard sidelights and a sternlight (required for vessels over 20 meters, and must be shown if over 7 meters) but *may* also exhibit the optional combination lantern showing **red over green** lights at the top of the mast. This specific vertical configuration (red over green) is designated solely for identifying a sailing vessel underway.
**Why the other options are incorrect:**
* **A) vessel on pilotage duty:** A vessel engaged in pilotage duty (Rule 29) displays **white over red** all-round lights.
* **B) law enforcement vessel:** While law enforcement vessels often use special flashing blue lights (under Inland Rules), the internationally recognized signal lights for common vessel statuses do not use the red over green configuration. A vessel showing its normal navigation lights would use standard power-driven vessel lights.
* **D) vessel engaged in fishing:** A vessel engaged in fishing (Rule 26) displays **red over white** all-round lights (with the apex of the cones touching). The green over red configuration is not used for fishing vessels.