What is the calculation involved in the 3-minute rule?

The calculation associated with the 3-minute rule is derived from the relationship between speed, distance, and time. In maritime navigation, this rule helps you estimate how far a vessel will travel in three minutes, which is essential for collision avoidance and for planning safe navigation, especially in busy waterways.

The correct calculation states that the distance traveled in 3 minutes equals the vessel's speed expressed in knots multiplied by 100, which gives you the distance in nautical miles. However, when considering speed in knots, multiplying it by 20 will provide the distance in nautical miles traveled in 1 minute (since 60 minutes divided by 3 minutes equals 20).

To calculate the distance traveled in 3 minutes, the formula becomes Speed (in knots) x 3 (minutes). Therefore, this calculation yields the distance in nautical miles traveled in a 3-minute span at a given speed.

This is why the option stating that the distance equals speed multiplied by 1200 is appropriate when considering speed in statutory miles or non-nautical terms for distances that convert correctly, but the practical maritime context typically emphasizes the Speed x 3 formula approach. It enhances a mariner's ability to react quickly and accurately when needing to assess distance over a short time frame