What type of line is used to represent low-water lines on a hydrographic survey?

The line used to represent low-water lines on a hydrographic survey is typically illustrated with a designation that shows its significance and helps distinguish it from other features on the map. In hydrographic surveys, different line styles are employed to signify various water levels and conditions.

A low-water line indicates the elevation of the water surface during low tide or low water conditions, which is crucial for navigation and understanding the water body's characteristics. The term "the next heaviest line" usually corresponds to a line weight that is more prominent than lighter marks but not the heaviest, thereby providing a clear, yet non-dominant visual context. This approach helps in maintaining clarity in the survey while also enabling mariners and navigators to easily interpret important navigational data.

By using a line weight that is visually distinguishable without overwhelming the chart, surveyors can effectively convey crucial information about the navigable depths and safety conditions present at low water levels. This is essential for safe passage and planning in marine environments.