🔍 Key Concepts

• Duration of light display in Rule 20 (Application) of the Navigation Rules • The difference between when lights are required and when they are permitted • How lights relate to day shapes/day signals

💭 Think About

• Ask yourself: Besides sunset to sunrise, under what other conditions might the Rules allow (not require) lights to be shown? • Think: Are lights and day shapes alternatives to each other, or can they be used at the same time? • Consider: Is there any situation in the Rules where a vessel is told it may turn off lights just because no other traffic seems to be around?

✅ Before You Answer

• Verify in Rule 20 whether lights may be exhibited in daylight under certain conditions (e.g., reduced visibility). • Check if Rule 20 links day signals and lights as "one or the other" or allows/mentions both together. • Confirm whether the Rules ever authorize extinguishing required lights at night simply because a vessel believes no one else is nearby.