What constitutes 'restricted visibility' for boaters?

Restricted visibility for boaters primarily refers to conditions where sight distance is significantly reduced. This situation often arises due to environmental factors such as fog, mist, or heavy rain. These elements can obscure a boater's ability to see other vessels, navigation markers, and any potential hazards in the water, making it critical to exercise increased caution and adhere to specific navigation rules during such times.

In contrast, clear weather conditions would define an environment where visibility is optimal, which does not fit the criteria for restricted visibility. High winds and tides may affect boating dynamics and safety, but they do not inherently limit visibility. Lastly, open water without obstacles indicates a safe and visible environment, thus clearly not aligning with the idea of restricted visibility. Therefore, fog, mist, or heavy rain directly correlates with the conditions that define restricted visibility for boaters.