🔍 Key Concepts

• Special identification lights used by U.S. Navy submarines when surfaced at night • Difference between navigation lights (red/green/white) and special-purpose identification lights • Where this is found: Annex I and U.S. Inland modifications in the Navigation Rules

💭 Think About

• Which colors are already used for normal sidelights and stern/masthead lights, and would that cause confusion if reused for a special ID signal? • Think about which color is commonly reserved in U.S. practice for special or law‑enforcement identification (not basic running lights). • Ask yourself: would the Navy want a color that clearly stands out from ordinary merchant and fishing vessels at night?

✅ Before You Answer

• Verify which light color is not a standard running light (port, starboard, stern, masthead). • Confirm that the light is intermittent flashing, not fixed or continuous, and strictly for identification. • Check U.S. specific provisions in the Inland Navigation Rules for naval vessels and submarines.