Aquaculture Engineering

Methods of ranging - Direct Ranging

Unit 1- Surveying

Ranging, types of ranging

Methods of Ranging:
There are two methods of ranging

• Direct ranging
• Indirect ranging

Direct ranging:
Direct ranging is done when the two ends of the survey lines are intervisible. In such cases ranging can either be done by eye or through some optical instruments such as line ranger or a Theodolite.

Ranging by eye:

Let A and B be the two points at the ends of a survey line. One ranging rod is erected at the point ‘B’ while the surveyor stands with another ranging rod at point ‘A’ holding the rod at about half meter length. The assistant then goes with another ranging rod and establishes the rod at a point approximately in the line with AB, at a distance not greater than one chain length from ‘A’. The surveyor at ‘A’ then signals the assistant to move transverse to the chain line, till he is in line with A and B. Similarly other intermediate points can be established.