46 CFR §32.56-10

1. (a)No navigation position may be above the cargo area unless it is approved by the Commandant as necessary for the safe operation of the vessel.
2. (b)Each navigation position that is above the cargo area must be separated from the deck by an unenclosed space that extends at least 2 meters (6.6 feet) from the deck to the navigation position.
3. (c)Openings to navigation positions above cargo areas, except air locks, must be at least 2.4 meters (7.9 feet) above the deck.