Watertight doors and watertight hatches must be marked on both sides in clearly legible letters at least 25 millimeters (1 inch) high: ``WATERTIGHT DOOR--KEEP CLOSED'' or ``WATERTIGHT HATCH--KEEP CLOSED'', unless such markings are deemed unnecessary by the cognizant OCMI. [CGD 85-080, 61 FR 935, Jan. 10, 1996, as amended by CGD 97-057, 62 FR 51047, Sept. 30, 1997]