🔍 Key Concepts

• Review Rule 27 – Vessels Not Under Command or Restricted in Their Ability to Manoeuvre in the Navigation Rules. • Recall the special day shapes used for dredging or underwater operations to indicate the safe and obstructed sides. • Compare the standard shapes for not under command, towing over 200 meters, and dangerous cargo with what you see in the illustration.

💭 Think About

• Look at each vertical line of shapes in the illustration. What does ball–diamond–ball mean by itself? • On a dredge, how are two balls and two diamonds used to mark the side where you must NOT pass and the side where you MAY pass? • Which of the answer choices involves a situation where you would see three separate groups of shapes on one vessel rather than just one group?

✅ Before You Answer

• Verify from Rule 27 that two black balls in a vertical line indicate a particular vessel status. • Verify from Rule 27 that ball–diamond–ball indicates a vessel restricted in her ability to manoeuvre. • Confirm which type of vessel operation combines ball–diamond–ball, two balls, and two diamonds at the same time.