ALL vessels used for commercial purposes 24m or over are required to have a loadline.
A loadline does not measure draft, it is a measure of freeboard, or reserve buoyancy. The freeboard is calculated on a state of loading which will leave the vessel still able to float if a compartment is breached.
The loadline rules came into being in 1894, though the present rules that are now in force are dated 1966.
DRAFT MARKS.
Now mainly metric, the metric marks read every 20cm. the marks are 10cm high.ie
2.40
2.20
2.00
The base of the numbers is as read ie 2.0 is 2metres. The top of the numbers are the odd readings ie top of 2.20 is 2.3m.
imperial marks are 6 inches apart, ie the bottom is the number read again, XI is 11 feet, the top of the XI is 11 feet 6 inches.
Andy