How can vessels close to shore be affected by vertical shadowing?

• A. They can see higher mountains more easily because of stabilization.
• B. They may see inland mountains clearly with practice.
• C. They experience no radar shadowing near shore.
• D. They may not be able to see higher mountains due to shadowing.

Answer: (D)

Vertical shadowing happens when tall terrain between your ship and a distant feature blocks the radar beam in the vertical plane. When you’re near shore, inland mountains lie at elevations that require the radar to look upward at certain angles. If those mountains rise above the line of sight of the radar beam, they shadow anything behind them at higher elevations. In practical terms, the radar may not pick up higher mountains inland because the nearer terrain obstructs the beam, creating a shadowed area. This is why vessels close to shore can lose sight of higher mountains due to that shadowing, even though the terrain at lower elevations or closer to shore might be visible. The effect depends on radar height, beam elevation angles, terrain height, and distance.