Aquaculture Engineering

Experiment No 4 - To erect a perpendicular to chain line

Practical - 1
Experiment 4 - To erect a perpendicular to chain line

To erect perpendicular to a chain line from a point on it

AB is the chain line. It is required to erect a perpendicular to the chain line at point ‘C’ on it. Establish a point ‘E’ at a distance of 3m from ‘C’. Take 10m tape and put the zero (0) end of the tape at ‘E’ and the 10m end at ‘C’. The 5th and 6th meter marks of the tape are brought together to form a loop of 1m. The tape is now stretched tight by fastening the ends E and C. The point ‘D’ is thus established. Angle DCE will be 90º.

To drop a perpendicular to chain line from a point outside it

AB is the chain line. It is required to drop a perpendicular to a chain line AB from point ‘D’ out side it. Select any point ‘E’ on the chain line. With ‘D’ as center, and DE as radius, draw an arc to cut the chain line at F. Bisect EF at ‘C’ and then CD is perpendicular to chain line AB.