What were the limitations of using lead/sounding lines for depth measurements?

Lead lines, also known as sounding lines, have significant limitations primarily related to the labor-intensive and time-consuming nature of their use. When using lead lines, surveyors must manually lower the line into the water until it reaches the seabed, then retrieve it to measure the depth. This often requires physical effort and can be quite slow, especially over large areas or in challenging sea conditions.

Additionally, recording depths using this method does not provide real-time data, meaning surveyors must take and compile measurements sequentially, which can greatly expand the duration of a survey.

Other options, while they may touch on aspects of lead line usage, do not fully encapsulate the significant delays and physical demands associated with this traditional method. The reliance on straightforward technology means that while it is not overly costly, it does not provide the efficiency or speed required for extensive or modern surveying tasks compared to contemporary methods such as echo sounding or multi-beam sonar.