🔍 Key Concepts

• Rule 25 – Sailing Vessels and Vessels Under Oars in the Navigation Rules • Difference between required lights and optional additional lights for sailing vessels • Special provisions for sailing vessels under 20 meters vs. 20 meters and over

💭 Think About

• First decide which lights a sailing vessel underway MUST show at night (think: what replaces the power-driven vessel’s masthead light?). • For each choice, ask: is this light (or these lights) described in Rule 25 as mandatory, optional in addition, or allowed only for vessels under 20 meters? • Think about when a white masthead light is used on a sailing vessel and what that says about her means of propulsion.

✅ Before You Answer

• In Rule 25, identify exactly which lights a sailing vessel of 20 meters or more must exhibit: look for sidelights and which white light is specified at the stern. • Check whether the red over green at the masthead is described as "may exhibit" (optional) or "shall exhibit" (required). • Verify which size of sailing vessel is permitted to use a combined lantern (tricolor) and whether that option applies to vessels over 20 meters.