What does the 1 minute rule help calculate?

The 1 minute rule is a navigational technique used to estimate distance based on speed. Specifically, it helps calculate the distance traveled in nautical miles over the course of one minute when moving at a certain speed in knots. Since one knot is defined as one nautical mile per hour, if a vessel is traveling at a speed of, for example, 10 knots, it will cover approximately 1.67 nautical miles in ten minutes. Thus, in one minute it would cover about 0.167 nautical miles, which can also be converted to feet for more detailed navigation.

This rule is particularly valuable for making quick calculations while underway, allowing mariners to effectively estimate how far they have traveled during a specific time, especially when navigating in constrained or busy waterways. So, when using this rule, a vessel's speed in knots translates directly into a measurable distance over time, making it a practical tool for mariners.