🔍 Key Concepts

• Masthead light definition and where it is normally placed (see Navigation Rules, Rule 21 and Annex I on positioning of lights) • The special allowances in Annex I for vessels where it is not practicable to place the masthead light on the fore‑and‑aft centerline • The difference between a vessel’s type of work (trolling, air‑cushion, etc.) and a vessel’s hull/structural design (special construction)

💭 Think About

• Which option describes a situation where it might be physically difficult or impractical to mount a masthead light exactly on the centerline of the vessel? • Look at which answer choices describe what the vessel is doing versus how the vessel is built—which of those is the focus of the Annex I exception for masthead light location? • Think about whether small size alone (like a 12‑meter power‑driven vessel) usually allows the masthead light to be moved off the centerline, or whether the rules keep the centerline requirement unless a specific exception applies.

✅ Before You Answer

• Verify in Annex I of the Navigation Rules that masthead lights are generally required on the fore‑and‑aft centerline of the vessel. • Check which category the rules specifically say may have the masthead light displaced from the centerline when it is impracticable to place it on the centerline. • Make sure you are not confusing the rules for additional lights (like air‑cushion vessel’s special lights or fishing lights for trolling) with the rule about moving the masthead light off the centerline.