Aquaculture Engineering (2+1)

Obstacle to chaining and ranging - Obstacle to chaining but not ranging

Unit 1- Surveying

Chain surveying

Obstacle to chaining and ranging

Obstacle to chaining but not ranging

There are two types of obstacle in this case

• When it is possible to chain round the obstacle. E.g., pond.
• When it is not possible to chain round the obstacle. E.g., river

When it is possible to chain round the obstacle

Select two points A and B on either side (Fig(a)). Set out equal perpendiculars AC and BD. Measure CD; then CD=AB.

II Method
Set out AC perpendicular to the chain line (Fig(b)). Measure AC and BC. The length AB is calculated from the relation.