🔍 Key Concepts

• IALA-B lateral system used in U.S. waters • Relationship between light/buoy color and the dayboard/daymark shape and color • Direction of buoyage on the Mississippi River (AHP: Above Head of Passes)

💭 Think About

• When you are going upstream on the Mississippi (increasing AHP), which side are red aids on, and which side are green aids on? • For that side of the channel, what is the standard daymark shape and color in the IALA-B system? • Does a lighted aid at a river mile usually have the same color/shape dayboard as the color of its light?

✅ Before You Answer

• Confirm the direction of buoyage on the river at that mile mark • Match red vs. green with triangle vs. square daymarks in IALA-B • Verify that a lighted river aid normally uses a colored dayboard, not a white one