What formation is used in a wider waterway when expecting threat activity from the strong side, providing a good field of fire?

The formation that is optimal for a wider waterway when expecting threat activity from the strong side, while also providing a good field of fire, is the echelon left and echelon right formation. This arrangement allows vessels to position themselves strategically, ensuring that they can cover a broader area and respond effectively to threats from the strong side. By fanning out to either side, the vessels in this formation create overlapping fields of fire, allowing for better mutual support and defense.

In this scenario, the echelon formation provides both an offensive posture and enhances the security of the vessels by ensuring that each is protected by the others, maximizing their collective firepower. This is especially crucial in a tactical environment where threats may emerge unexpectedly, and a quick, coordinated response is essential.

Other formations, such as line ahead, would limit the field of fire and make the vessels more susceptible to concentrated attacks. The diamond formation is more suited for specific tactical situations rather than broad area coverage in challenging environments. Similarly, a column formation minimizes the field of view and hampers the ability to provide effective fire support against threats.