Rule 55S 3700 Series Automatic Submersible Bilge Pump - 3700 GPH

The Rule 55S is an automatic submersible bilge pump rated at 3,700 GPH (14,010 LPH; approx. 233 litres/minute). It checks for water every 2.5 minutes and runs when resistance at the impeller indicates water is present, so no separate float switch is required.

The Rule 55S combines a fully submersible centrifugal bilge pump with integral automatic control. During normal operation the pump briefly checks for water at 2.5-minute intervals and continues running when water is detected. This eliminates the need for a separate float switch while retaining a compact installation footprint.

Product Identification

• Brand: Rule
• Product name: Rule 55S 3700 Series Automatic Submersible Bilge Pump - 3700 GPH
• Model / part number: 55S
• Marine Scene SKU: CW-55S
• Product category: Automatic submersible bilge pump
• Rated open flow: 3,700 GPH (14,010 LPH; approx. 233 litres/minute)
• Voltage: 12V DC
• Automatic operation: Yes - integral timed water-sensing operation; no separate float switch required
• Discharge hose size: 38 mm (1-1/2 in)
• Current draw: 15.5A at 12V; 20.0A at 13.6V
• Recommended fuse: 25A
• Quantity supplied: One pump

What Is the Rule 55S Bilge Pump Used For?

This pump is used for automatic removal of nuisance water from larger yachts, motor cruisers and high-capacity bilge installations. It is intended for permanent marine installation and should be selected by required flow, supply voltage, discharge-hose size and expected discharge head.

What Is Included?

• One Rule automatic submersible bilge pump
• Integral timed water-sensing control
• Integral or snap-lock strainer base
• Factory-fitted marine-grade electrical leads

What Is Not Included?

• Discharge hose, through-hull fitting and hose clips
• Optional panel switch
• Cable extensions, waterproof connectors and circuit-protection fuse
• Installation hardware not supplied with the packaged pump

Which Boats and Bilge Systems Is This Pump Suitable For?

• Suitable for larger yachts, motor cruisers and high-capacity bilge installations.
• Connect to 38 mm (1-1/2 in) discharge hose.
• Choose the variant that matches the vessel electrical system: 12V.
• A compatible Rule panel switch may be fitted where manual override or status control is required.
• No separate external float switch is needed for automatic operation.

How Does the Automatic Operation Work?

Yes - integral timed water-sensing operation; no separate float switch required The published automatic check cycle is pump checks for water every 2.5 minutes. Separate float switch required: No.

How Do I Select the Correct Pump?

Confirm the complete installation rather than selecting by nominal GPH rating alone:

• Supply voltage: 12V DC
• Rated open flow: 3,700 GPH (14,010 LPH; approx. 233 litres/minute)
• Discharge hose: 38 mm (1-1/2 in)
• Installed space: 209 x 124 mm (H x W)
• Circuit protection: 25A
• Flow at 1 m head: 2,900 GPH (10,977 LPH)
• Flow at 2 m head: 2,450 GPH (9,274 LPH)

Does the Published Flow Equal the Installed Flow?

No. The nominal capacity is an open-flow rating. Actual output reduces as discharge head, hose length, bends, restrictions and electrical voltage drop increase. Use the published flow-at-head figures where available and keep the discharge route as short and unrestricted as practical.

Construction and Design

• Replacement strainer part number: 279
• Backflow prevention: No integral non-return valve stated
• Thermal protection: Built-in thermal cut-off
• Ignition protection: Yes
• Standards: CE; ISO 8849 marine bilge-pump standard

Installation and Safety

Mount the pump at the lowest practical point of the bilge while maintaining access for cleaning. Wire directly through the specified fuse and follow the manufacturer wiring diagram for any manual-override lead. Keep electrical joints above the maximum bilge-water level, minimise hose length and bends, prevent siphoning, and test automatic operation before leaving the vessel unattended.

Maintenance

Inspect and test the complete bilge-pump system regularly and before extended passages. Reduced flow, repeated fuse failure, unusual noise or slow switching requires investigation before the vessel is used.

• Remove debris from the strainer and impeller area.
• Inspect the discharge hose, clips, through-hull and anti-siphon arrangement.
• Check the wiring, fuse, terminals and control switch for heat, corrosion or damage.
• Keep the automatic sensor or float-switch movement clear of oil, dirt and debris.
• Test manual and automatic operation after cleaning or service.
• Replace damaged components rather than operating an unreliable bilge system.

Key Features

• Nominal open-flow capacity: 3,700 GPH (14,010 LPH; approx. 233 litres/minute)
• Integral automatic water checking every 2.5 minutes
• No separate float switch required
• Built-in thermal cut-off
• Easy-clean strainer and accessible impeller cavity
• Ignition protected; CE and ISO 8849 compliant

Frequently Asked Questions

Does this automatic pump need a float switch?
No. The automatic control is built into the pump.

Why does the pump run briefly when the bilge appears dry?
The pump checks for water at 2.5-minute intervals. It stops after the short check when no water resistance is detected.

How do I choose between the available variants?
Select the model that matches the vessel supply voltage: 12V. Also confirm the hose size, fuse rating and available installation space.

Does the stated flow equal the installed flow?
The stated capacity is an open-flow rating. Actual output falls as discharge head, hose length, bends, restrictions and voltage drop increase.

Specifications

Flow ratings are nominal open-flow figures. Installed output will reduce as discharge head, hose length, bends, restrictions and supply-voltage loss increase.

Flow ratings are nominal open-flow figures. Installed output will reduce as discharge head, hose length, bends, restrictions and supply-voltage loss increase.