🔍 Key Concepts

• Rule 20 – Application of Lights and Shapes in the Navigation Rules • Difference between lights being required to be ON versus capable of being shown • How the Rules treat hours of darkness and restricted visibility

💭 Think About

• Think about when vessels are legally required to have their navigation lights displayed versus when they must simply be ready for use. • Which option best matches the wording in Rule 20 about the period from sunset to sunrise and conditions of restricted visibility? • Consider whether the Rules ever require navigation lights to be exhibited in daylight under any special conditions.

✅ Before You Answer

• Check the exact phrase in Rule 20(a)–(c) regarding the period "from sunset to sunrise". • Verify if the Rules say that lights must be ready for immediate use at all times, or actually shown at all times. • Confirm whether restricted visibility during the day changes the requirement from just being ready to actually being displayed.