Section 108.661 - Unit markings: Draft marks(a) Each unit must have draft marks for each foot of immersion- (1) If the unit is a surface unit, on both the port and starboard sides of the stem and the stern-post or rudderpost or at any other place at the stern of the unit as may be necessary for easy observance;(2) If the unit is a self-elevating unit, near each corner of the hull but not more than 4 required; and(3) If the unit is a column-stabilized unit, on each corner column, continuing to the footing or lower displacement hull.(b) The bottom of each mark must be at the draft indicated by that mark.(c) Each mark must be-(1) In numerals 15 centimeters (6 inches) high; and(2) In contrasting color to the background.(d) For the purposes of this section, "draft" means the distance from the bottom of the keel or the lowest shell plate on the outer surface of the unit to the surface of the water, except that where a unit has a permanent appendage extending below the bottom of the keel, "draft" means the distance from the lowest part of the appendage to the surface of the water.(e) In cases where draft marks are obscured due to operational constraints or by protrusions, the vessel must be fitted with a reliable draft indicating system from which the draft can be determined.CGD 73-251, 43 FR 56808, Dec. 4, 1978, as amended by CGD 89-037, 57 FR 41823, Sept. 11, 1992