How to Make Underwater Depth Gauges

An underwater depth gauge is a tool fisherman, divers and others who conduct water-based activities commonly use. Gauging depth is easy with modern electronic sonar equipment, but manual depth gauges are also valuable and easy to construct. The manual gauge is most effective at 100 feet or less, but greater depths are possible with a long line and the patience to reel and track the distance.

Things You'll Need

  • Wooden dowel
  • Fishing line
  • Lead sinker
  • Black marker
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Instructions

    • 1

      Tie a fishing line to a 1-foot-long wooden dowel or stick.

    • 2

      Measure 1 foot of line and mark the measurement with a black pen. Wrap the line around the dowel and count the number of wraps until you reach the marking. Record or memorize the number of wraps per foot.

    • 3

      Wrap 50 to 100 feet of line on the stick for normal lake and river depths. Tie the free end of the line to a 1-ounce lead sinker.

    • 4

      Drop the sinker in the water and lower the weight until it makes contact with the bottom. You know when contact is made because the line loses tension.

    • 5

      Wrap the line on the stick and count the number of wraps. Stop when the sinker is retrieved. Divide the total number of wraps by the number of wraps per foot to determine the depth in feet.