46 CFR § 28.250
High water alarms
April 15, 2021
On a vessel 36 feet (11.8 meters) or more in length, a visual and audible alarm must be provided at the operating station to indicate high water level in each of the following normally unmanned spaces:
(a) A space with a through-hull fitting below the deepest load waterline, such as the lazarette;
(b) A machinery space bilge, bilge well, shaft alley bilge, or other space subject to flooding from sea water piping within the space; and
(c) A space with a non-watertight closure, such as a space with a non-watertight hatch on the main deck.