When approaching another vessel, which factor does NOT indicate a risk of collision?

The factor that does not indicate a risk of collision is having a decreasing range. When the range between two vessels is decreasing, it typically suggests that they are approaching each other, which is an important consideration when assessing collision risk.

When you see both sidelights of another vessel, it indicates that the vessels are on a collision course, as it signifies that you are looking at the other vessel's port and starboard sides simultaneously. Maintaining a constant bearing suggests that the vessels are neither closing in nor moving apart, which is a strong indicator of a potential risk of collision.

In contrast, changing course dramatically could involve a sudden maneuver that might indicate an attempt to avoid a collision, but does not directly suggest that a collision is imminent. Therefore, it’s important to carefully analyze these factors in conjunction with navigation rules to ensure safety on the water.