🔍 Key Concepts

• Rule 30 – Anchored Vessels and Vessels Aground (Navigation Rules) • Day shapes for vessels aground versus restricted in ability to maneuver (RAM) and towing • How many shapes are displayed, and in what pattern (vertical line, triangle, single shape, etc.)

💭 Think About

• First, recall exactly what day shapes a vessel aground must display. How many shapes are there, what are they, and how are they arranged? • Next, think about each listed vessel type and recall its normal day shapes: does it use the same number of shapes in a straight vertical line, or a different pattern? • Ask yourself whether any of the listed vessels uses a vertical string of the same shapes, or whether they use combinations (like ball–diamond–ball) or different arrangements.

✅ Before You Answer

• Verify from Rule 30 what the day shape for a vessel aground is (number of balls and their arrangement). • For towing a submerged object, verify whether the shape is a ball, a diamond, or a combination – and how many. • For dredging or hydrographic survey vessels, confirm if they are treated as restricted in ability to maneuver (RAM) and what that RAM day shape pattern is (ball–diamond–ball or something else).