Deep-sea lead

The deep-sea lead, called the dipsey lead, is the heavy hand-sounding lead once used for depths beyond the hand lead, out to about 100 fathoms or more. It is a tapered lead weight of 14 to 28 pounds on a marked deep-sea lead line, the hollow base armed with tallow to bring up a sample of the bottom for the chart’s bottom-quality note. The line was streamed from forward and the depth read as the ship ran up to it. Echo sounders have replaced it for routine work, but the principle survives in the lead line carried for shallow checks, and the term still appears in chartwork and the history of sounding.