Which factor is NOT considered in determining the risk of collision?

Determining the risk of collision requires analyzing several critical factors that affect the interactions between vessels. The speed of the vessels involved plays a significant role, as faster vessels will have less time to react to each other in close quarters. Visibility conditions are equally crucial, as poor visibility can hinder a mariner's ability to see other vessels, which raises the risk of collision. Additionally, the angle of approach between vessels is essential, since certain angles may present more potential for danger based on each vessel's maneuverability and course.

In contrast, the color of the vessels' lights does not impact the risk of collision in a meaningful way regarding navigational safety or situational awareness. While colored lights are used to identify the type and size of vessels and their navigation status, they do not directly influence how likely a collision is to occur. Thus, when assessing the risk of collision, the color of the lights is not a factor that contributes to situational awareness or collision avoidance strategies.