Aquaculture Engineering (2+1)

Obstacle to chaining and ranging - Obstacle to both chaining and ranging

Unit 1- Surveying

Chain surveying
Obstacle to chaining and ranging

Obstacle to both chaining and ranging

I Method
Building is the typical example for this type of obstacle.

Select two points A and B on one side of the obstacle. Erect perpendiculars AC and BD of equal length. Join CD and prolong it past the obstacle. Choose two points E and F on the line CD and erect perpendiculars EG and FH equal to that of AC or BD. Join GH and prolong it. Measure DE. BG = DE.

II Method

Select a point A and erect a perpendicular AC of any convenient length(Fig(b)). Select another point B on the chain line such that AB=AC. Join B and C and prolong it to any convenient point D. At D, set a right angle DE such that DE=DB. Choose another point F on DE such that DE=DC. With F as centre and AB as radius, draw an arc. With E as centre, draw another arc of the same radius to cut the previous are in G. Join GE which will be in range with the chain line. Measure CF. Then AG=CF.

Animation