Overview

The Attwood Marine 4730-4 is a 12V heavy-duty bilge pump that moves up to 1700 GPH at open flow, draws less than 6 amps, and uses a 1-1/8 in. I.D. discharge hose. It is fully submersible and supplied with a 36 in. wire lead, so it fits straightforward replacements and new bilge layouts where you need a higher-capacity pump without stepping up to a larger 24V system.

This pump makes sense when a lighter bilge pump is cycling too often, when an older 1500 GPH unit is no longer enough, or when the bilge space sees more abuse than normal weekend use. The anti-airlock nozzle, rotating outlet, and locking base help in real bilge compartments where hose routing is tight and access is limited.

The housing and internal materials are built for bilge areas that can see engine oil, detergent washdowns, vibration, and repeated duty cycles. That matters on fishing boats, cruisers, and workboats where the pump may spend years in a wet and dirty part of the hull.

Key features

• 12V heavy-duty electric bilge pump with 1700 GPH open-flow output
• Current draw stays under 6 amps, which helps on boats where power budget matters
• 1-1/8 in. I.D. outlet fits a common hose size for this capacity range
• Anti-airlock nozzle helps clear trapped air from the discharge side
• Rotating outlet and locking base give more freedom when routing hose in a tight bilge
• Fully submersible body for installation low in the hull
• 36 in. wire lead for hardwiring into the boat’s bilge circuit
• Tinned and caulked wire helps resist corrosion and water damage in marine wiring runs
• Exterior materials resist engine oil, aggressive detergents, and hose plasticizers
• Marine ignition protected and built to meet common marine standards including ABYC H-22, ISO 8846, ISO 8849, and CE

Compatibility and fit

This model is for 12V DC boats and is best matched to a bilge system using 1-1/8 in. discharge hose. A 10A fuse is the right size for the pump circuit. Before ordering, check your hose diameter, wiring run, and the space around the mounting area so the outlet can rotate cleanly without kinking the hose.

It is a non-automatic bilge pump. On boats that need unattended bilge operation, it can be paired with a separate float switch to create an automatic setup while keeping this pump as the main water-moving component.

Installation and setup

Mount the pump at the lowest practical point in the bilge and keep it below the water source so it can prime correctly. The 36 in. wire lead gives enough length for many direct replacements, but on longer runs you will still want clean marine-grade butt connections and proper support for the wiring above the bilge waterline.

Hose routing has a direct effect on output. This pump is rated at 1700 GPH at open flow, but flow drops to about 1300 GPH at 3.3 ft of head and about 950 GPH at 6.7 ft, so long vertical runs and unnecessary bends will reduce what you see in service.

Use on board

This is a good match for owners replacing an aging high-capacity bilge pump, builders rigging a 12V boat with a heavier-duty manual bilge circuit, and crews running hulls that spend long hours underway or at the dock in wet conditions. It also suits boats where the bilge compartment is compact but the pump still needs to cope with repeated cycling and dirty water conditions.