Barrier search is used under which condition?

• A. Weak Currents
• B. Strong Current
• C. Fog
• D. Calm Seas

Answer: (B)

Barrier search is chosen when there is a strong current. In these conditions, objects or persons in the water drift quickly downstream, and a visible boundary (such as a shoreline, breakwater, or other barrier) tends to concentrate drift against that boundary. The pattern uses a line or barrier across the current so that sweepers move and scan toward the barrier, repeatedly crossing the flow path. This confines the search to the corridor where the target would be carried by the current and against the barrier, increasing the chance of detection before the object drifts out of range.

In calmer seas, drift is minimal and a different search pattern that covers the area methodically without relying on a boundary is typically more effective. Fog primarily affects visibility and navigation, not the drift behavior the barrier pattern exploits.