🔍 Key Concepts

• Day shapes in the Navigation Rules for vessels not under command, restricted in their ability to maneuver, aground, and at anchor • How many black balls are required for a vessel aground vs just at anchor • Difference between lights at night and shapes by day for a vessel aground

💭 Think About

• First recall the day shape for a vessel at anchor alone. Then consider what additional indication is required when that vessel is aground. • Think about whether a vessel aground is considered restricted in her ability to maneuver or in a different special condition with its own day shape pattern. • Ask yourself: Is the day shape for a vessel aground simply the same as at anchor, or is it that shape plus something extra to show the danger?

✅ Before You Answer

• Check the Navigation Rules Annex that shows day shapes for various conditions and count the number of black balls used for each condition. • Verify that you are thinking of day shapes, not the number of lights shown at night for the same condition. • Confirm whether the shape for a vessel aground combines the indication for being at anchor with an additional ball to indicate she is aground.