46 CFR §28.560

1. (a)Each opening in a deck or a bulkhead that is exposed to weather must be fitted with a weathertight or a watertight closure device.
2. (b)Except as provided in paragraphs (c) through (f) of this section, each opening in a deck or a bulkhead that is exposed to weather must be fitted with a watertight coaming as follows:
   1. (1)For a vessel 79 feet (24 meters) or more in length, the coaming must be at least 24 inches (0.61 meters) in height; or
   2. (2)For a vessel less than 79 feet (24 meters) in length, the coaming must be at least 12 inches (0.30 meters) in height.
3. (c)A coaming to a fish hold that is under constant attention when the closure is not in place need only be 6 inches (0.15 meters) in height.
4. (d)The coaming of an opening fitted with a quick-acting watertight closure device need only be of sufficient height to accommodate the device.
5. (e)Except on an exposed forecastle deck, a coaming is not required on a deck above the lowest weather deck.
6. (f)Each window and portlight located below the first deck above the lowest weather deck must be provided with an inside deadlight. Each deadlight must be efficient, hinged, and arranged so that it can be effectively closed watertight.
7. (g)An opening in a vessel below the weather deck which is used for discharging water or debris resulting from processing or sorting operations must be fitted with a means to ensure the opening can be closed weathertight. This means of closing must be operable from a location which is outside the space containing the opening.