🔍 Key Concepts

• Western Rivers Aids to Navigation System and what "left descending bank" means (looking downstream). • Relationship between color and shape of daymarks (squares vs. triangles vs. diamonds) in the U.S. lateral system. • How "red" and "green" are used on opposite sides of the channel when going upstream vs. downstream on Western Rivers.

💭 Think About

• Visualize yourself traveling downstream on a Western River (from mile 100 to mile 99). The left descending bank is on which side of your vessel? Now, think about what color/shape marks that side of the channel. • Recall the standard U.S. lateral system: when returning from sea (or going upstream), which side are red aids on and which side are green aids on? Now reverse the direction (going downstream) and see what ends up on the left descending bank. • Separate the answers by both color and shape: which shapes (square, triangle, diamond) are typically used as lateral daymarks, and which color is assigned to the left or right side of the channel in river navigation?

✅ Before You Answer

• Confirm which direction "descending" refers to on a river (upstream vs. downstream). • Verify which color (red or green) is used for aids on the left side of the channel when moving downstream on Western Rivers. • Verify which shape (square vs. triangle) corresponds to that side in the U.S. lateral system, and whether diamonds are normally used as primary lateral daymarks.