46 CFR § 42.15-15
Positions of hatchways, doorways and ventilators
April 15, 2021
(a) For the purpose of this part two positions of hatchways, doorways and ventilators are defined as follows:
(1) Position 1: Upon exposed freeboard and raised quarter decks, and upon exposed superstructure decks situated forward of a point located a quarter of the vessel's length from the forward perpendicular.
(2) Position 2: Upon exposed superstructure decks situated abaft a quarter of the vessel's length from the forward perpendicular.
[CGFR 68-60, 33 FR 10060, July 12, 1968, as amended by CGFR 68-126, 34 FR 9014, June 5, 1969]