🔍 Key Concepts

• Western Rivers buoyage within the U.S. Aids to Navigation System • Meaning of group flashing (2) versus single flash or composite group flashing (2+1) • How lights are used to distinguish lateral marks (left/right bank, preferred channel)

💭 Think About

• Think about which type of aid to navigation especially needs a distinctive, easily recognizable light pattern to show mariners that something is different about that mark compared to others in the same area. • Ask yourself: on Western Rivers, how are the left and right descending banks normally marked—by color, numbers, shapes, or special light groups? Which of those features usually change when the buoy is indicating a special function like a preferred channel? • Consider where you would most need extra information at night: when simply following one bank, or when deciding which way to go at a channel split or junction?

✅ Before You Answer

• Review how left descending bank and right descending bank are identified on Western Rivers (colors, numbers, shapes) in the Light List or Aids to Navigation manuals. • Confirm the standard light characteristics for ordinary lateral buoys versus the special light characteristics assigned to junction or bifurcation marks. • Make sure you distinguish between group flashing (2) and composite group flashing (2+1), and what each is commonly associated with.