What is the look-ahead time interval based on?

The look-ahead time interval in navigation is generally calculated based on a factor of the fix interval. Using a multiple of the fix interval ensures that navigators can anticipate where a vessel will be positioned in the near future, allowing for better decision-making regarding course and speed adjustments.

Choosing a factor of two times the fix interval is ideal because it allows for a balance between responsiveness and accuracy. This duration provides enough time to observe trends in the vessel's movement while also being short enough to react to changing conditions. In essence, it grants navigators a forward-looking perspective while ensuring that the data is still relevant and timely, which is crucial for safe navigation.

Other intervals, such as three times or four times the fix interval, may introduce too much delay, which could lead to navigational inaccuracies as conditions change. Thus, using two times the fix interval as the look-ahead time interval is a best practice in sea navigation.