🔍 Key Concepts

• Rule 25 – Sailing Vessels Underway and Vessels Undergoing Towing or Pushing (Navigation Rules) • The definition of a vessel "under sail alone" vs. sailing vessel also being propelled by machinery • Required day shapes for a sailing vessel when the engine is in use or not in use

💭 Think About

• First decide: when both sails and engine are used (or ready for use), is the vessel considered a power-driven vessel or a sailing vessel under the Rules? • Next, think about what day shape is required to show that a sailing vessel is ALSO using its engine. • Finally, ask yourself: if the condition of propulsion changes (engine stopped), what must change about the day shape, if anything?

✅ Before You Answer

• Look up the exact wording in Rule 25(e) on a sailing vessel also being propelled by machinery. • Identify which choice describes the day shape for a sailing vessel under power (engine in use) versus under sail alone. • Verify whether the required action is to display or to remove that particular day shape when the engine is no longer in use.