46 CFR § 45.127
Position of structures, openings, and fittings
April 15, 2021
For the purposes of this part—
(a) Position 1 means in an exposed position on—
(1) The freeboard deck or a raised quarter deck;
(2) A superstructure deck or a trunk deck and forward of a point 1⁄4 L from the forward perpendicular; or
(3) A trunk deck whose height is less than Hs.
(b) Position 2 means—
(1) On a superstructure deck aft of a point 1⁄4 L abaft the forward perpendicular; or
(2) On a superstructure and trunk combination, that is Hs or more n height, aft or a point 1⁄4 L abaft the forward perpendicular.