46 CFR §182.530

1. (a)On a vessel of at least 7.9 meters (26 feet) in length, a visual and audible alarm must be provided at the operating station to indicate a high water level in each of the following normally unmanned spaces:
   1. (1)A space with a through-hull fitting below the deepest load waterline, such as a lazarette;
   2. (2)A machinery space bilge, bilge well, shaft alley bilge, or other spaces subject to flooding from sea water piping within the space; and
   3. (3)A space with a non-watertight closure, such as a space with a non-watertight hatch on the main deck.
2. (b)Vessels constructed of wood must, in addition to paragraph (a), provide bilge level alarms in all watertight compartments except small buoyancy chambers.
3. (c)A visual indicator must be provided at the operating station to indicate when any automatic bilge pump is operating.