Bilge Pump

A bilge pump is a water pump used to remove bilge water, the water that collects in the lowest part of a ship's hull, and because fuel can be present there, electric bilge pumps are built to avoid generating sparks. Modern installations often include a float switch that starts the pump automatically once water reaches a set level, and it is common to fit a backup pump mounted higher than the primary one so it activates only if the main pump is overwhelmed or fails. Ancient ships used force pumps made of wood or bronze, built from a cylinder, a piston and a set of valves, to clear bilge water and to fight fires, and the Archimedes screw was later put to the same task on larger vessels, turned by hand to lift water, a device still used today, including for irrigation.