To plot the line of a curved boundary or wall, you need to use simple measurements known as 'offsets'.

1. First plot the two ends of the boundary or wall concerned, using triangulation if necessary.
2. Next, take a sufficient length of garden twine attached to metal skewers and stretch this from one end of the feature to the other.
3. Starting at one end, take a measurement at right angles from the line to the boundary at fixed intervals (for example, every 1 m), clearly noting each measurement on the survey drawing.
4. When these offset measurements are linked up, the curve of the feature will be reproduced.