The "rule of 12s" is an important principle for navigating which type of water?

The "rule of 12s" is a crucial guideline for navigating tidal waters because it helps mariners understand the changes in water levels during the rising and falling of tides. This rule provides a rough estimate of how much the tide rises or falls in relation to the time from high and low water marks.

In tidal waters, the phenomenon of tides significantly impacts navigation, as it can affect depth and accessibility in certain areas, particularly in coastal environments or estuaries. Understanding the timing and magnitude of tides is essential for safe navigation, especially when entering or leaving harbors and navigating shallow waters.

In comparison, still waters, freshwater lakes, and rivers typically do not exhibit the same tidal effects, which means the "rule of 12s" does not apply to these types of water. Thus, the principle is specifically designed for use in tidal conditions where the timing and amplitude of water movement are critical for navigation and safety.