Definition

1. Noun:
   • A weighted line used to measure the depth of water: A "sounding line" is a nautical tool consisting of a line (rope) with a weight (lead) attached to its end. It is lowered into the water until the weight touches the bottom, allowing the depth to be measured by the length of line paid out.

Usage

• The primary use of a sounding line is for bathymetry—determining the depth of a body of water and the nature of the seabed.
• It is a traditional method of navigation and charting, largely replaced by electronic depth sounders in modern times.
• The process of using it is called "taking a sounding" or "sounding."

Examples

• Noun:
  • The sailor cast the sounding line overboard to check the depth before anchoring.
  • Early oceanographers relied on the sounding line to map the seafloor.

Advanced Usage

• "To heave the lead": This is a traditional phrase meaning to use a sounding line (specifically a "hand lead") to take a depth measurement.
  • The captain ordered the sailor to heave the lead as they approached the unfamiliar coast.

Variants and Related Words

• Lead line: Another common term for a sounding line, emphasizing the lead weight.
• Sounding lead: Refers specifically to the weighted end of the sounding line.
• Sounding: (Noun) The act of measuring depth or the depth measurement obtained.
  • The sounding indicated shallow water.

Synonyms

• Plumb line: While a plumb line is used in construction for establishing a vertical line, in a nautical context, it can be synonymous with a sounding line for determining depth.
• Depth line: A descriptive synonym.

Related Phrases

• Sounding pole / sounding rod: A pole marked with depth measurements, used in very shallow waters instead of a line.
• Echo sounding: The modern electronic method of determining depth using sound waves, which derives its name from the traditional method.

Noun

1. (nautical) plumb line for determining depth