Collection: Wedge

Bilge: evacuating and monitoring water aboard

The bilge is one of the least visible areas of a boat, but also one of the most critical for safety. A bilge pump must quickly remove water that accumulates at the lowest point, whether from seepage, rinsing, heavy condensation, a stuffing box, a circuit leak, or a more serious incident. A good system is not limited to the pump itself: it combines flow rate, electrical power, piping, control, alarm, and regular maintenance.

This collection includes bilge-related equipment for pumping, control, and monitoring. It falls under the Plumbing category and complements other pumps on board when the priority is water evacuation from the boat's lowest point.

Bilge pump and alarm: two complementary functions

• Pumping: remove water present in the bilge to the outside, with a flow rate suited to the boat and available voltage.
• Control: start or stop the pump, manually or automatically depending on the setup.
• Alerting: signal rising water levels or abnormal operation before the situation becomes critical.

The Rule 14 000 L/h 24 V submersible bilge pump meets installations requiring high flow in 24 V. The Mastervolt bilge pump alarm control panel series 3 adds a monitoring and alarm interface to better track the circuit's status.

Choosing a bilge pump

The advertised flow rate is not enough to size an installation. You must consider the discharge head, hose length, outlet diameter, pressure losses, available voltage, and the pump's actual position in the bilge. The higher the discharge or the longer the hose, the more the actual flow decreases.

• Voltage: choose a pump compatible with the boat's battery bank, 12 V or 24 V depending on the installation.
• Actual flow rate: base your decision on the installed flow rate, not just the nominal flow rate measured without a hose.
• Discharge head: anticipate the vertical distance to the hull outlet.
• Hose diameter: avoid constrictions that significantly reduce evacuation capacity.
• Accessibility: keep the pump removable to clean the strainer, inspect the impeller, and remove debris.

Installation: key considerations

The pump must be placed at the lowest useful point, on a stable surface, with an accessible strainer. The hose must connect to a properly located outlet, avoiding loops that trap water or fragile routing. In some setups, an anti-siphon valve or a higher outlet placement is necessary to prevent backflow.

Electrically, the circuit must be protected, correctly fused, and wired for the pump's current. A bilge pump often remains powered even when the boat is idle; the installation must remain clear, protected, and identifiable. A manual control at the helm and a visual or audible alarm significantly improve system status understanding.

Automatic activation and monitoring

A reliable bilge system must operate without immediate crew action but also provide warnings. A float switch, electronic sensor, or control logic can automate activation. The alarm signals rising water, a pump running too long, or a situation requiring visual inspection.

For cruising, work, or racing boats, redundancy is often relevant: a primary pump for routine water and a backup pump placed higher or with greater capacity for emergencies. The alarm panel then provides a simple status: the bilge is no longer in its normal state.

Common mistakes

• Selecting a pump based on nominal flow without accounting for hose-related losses and discharge head.
• Installing the pump in an inaccessible area, making it impossible to clean quickly.
• Using a hose that is too small, too long, or pinched by routing.
• Failing to install an alarm when the pump operates in an invisible compartment.
• Treating the bilge pump as a solution for a leak: it mitigates consequences but never replaces locating and repairing the source of the leak.

Skysat advice

A good bilge installation must remain easy to inspect: accessible pump, properly sized hose, protected electrical circuit, clear control, and visible alarm. We recommend regularly checking the strainer, activation, output flow, and absence of backflow. A neglected bilge pump rarely performs when it is most needed.