🔍 Key Concepts

• Navigation Rules Rule 25 – Sailing Vessels Underway and Underway + Making Way • The length cutoff for when a combined lantern is allowed on a sailing vessel • The difference between required (shall exhibit) lights and optional (may exhibit) lights, such as red over green

💭 Think About

• Check Rule 25 and identify which lights a sailing vessel of 20 meters must show when underway. Which lights are described with the word "shall"? • Look at the size condition for a combined lantern. Is a vessel that is exactly 20 meters included in the length range that may use it? • Determine whether the red over green masthead lights are described as optional or mandatory for sailing vessels. Then see which of the answer choices are truly required, not just allowed.

✅ Before You Answer

• Verify whether "less than 20 meters" includes or excludes a vessel that is exactly 20 meters in length. • Identify which of the listed lights are described as additional/optional in Rule 25 for sailing vessels. • Confirm that every light included in the answer you pick is explicitly required for a 20-meter sailing vessel underway, not just permitted.