Reading Draughts:
The following figure shows the draught marks between 11m and 12m. It means that the mark is submerged up to the level of the mark, measurement of draught being from the bottom up.
When the water is touching exactly the 11M mark at the bottom, only then is the draught read as 11m. anywhere above that is more than 11m.
The height of the mark being 20cm, therefore the top of the 11m mark would read a draught of 11.20 m.
The bottom of the decimal mark of 2 coincides with the top of the 11M mark and is to be read as 11.20m.
The decimal marks are each 10 cm in height.
Since the decimal marks are at – 2, 4, 5 and 8, the odd numbered decimal being ignored, thus the top of this 2 would read as 30 cm above the 11m mark or 11.30m.
If the water level were at a position between the top of 2 and the bottom of 4 then the reading would be 11.35m.
Rest of the marks are self explanatory.
If reading the draughts in choppy sea condition then the average of at least 5 readings would give a reasonable draught. Note do not read only the highest or the lowest since these may be due to out of the normal waves.
For loading to draught marks – or when being surveyed for load line compliance, the draught may be used to check for overloading or submerging the load line mark. However it should be remembered that it is the freeboard that is being checked.
For load line surveys the surveyor would mark a long baton (wooden) with the total length of the freeboard (summer) and others and then checks with the same against the deck line and the markings on the shipside (midship marks)