The deck line is a horizontal line 300 millimetres (12 inches)
in length and 25 millimetres (1 inch) in breadth. It shall be marked
amidships on each side of the ship, and its upper edge shall normally
pass through the point where the continuation outwards of the upper
surface of the freeboard deck intersects the outer surface of the
shell (as illustrated in Figure 1),
provided that the deck line may be placed with reference to another
fixed point on the ship on condition that the freeboard is correspondingly
corrected. The location of the reference point and the identification
of the freeboard deck shall in all cases be indicated on the International
Load Line Certificate (1966).
Figure 1 Deck Line