Table of Contents

• Why the Sahara S750 Is No Longer Available
• Attwood MK2 S800 #5509-7 as a Direct Replacement
  • Pump Capacity and Performance
  • Construction and Corrosion Resistance
• Seachoice 19276 Bilge Pump as an Alternative
• Bilge Pump Wiring and Hose Compatibility
  • Voltage and Electrical Requirements
  • Float Switch and Automatic Activation
• How to Test an Automatic Bilge Pump After Installation
• Comparison Table: Sahara S750 Replacement Options
• Which Replacement Is Right for Your Vessel
• Frequently Asked Questions

Last Updated: October 21, 2026

Why the Sahara S750 Is No Longer Available

The Attwood Sahara S750 bilge pump was a workhorse for recreational boat owners and commercial operators alike, but finding a direct replacement for the discontinued sahara s750 bilge pump has become a real challenge. If your vessel still runs one, you've likely relied on its straightforward automatic operation and proven durability in both freshwater and saltwater environments. But Attwood discontinued this model, and finding a direct replacement has become a real challenge for boat owners who need the same capacity and fit.

The good news: you don't need to search endlessly or settle for a pump that doesn't match your boat's electrical system or mounting pattern. First Choice Marine carries verified replacement options that address the S750's discontinuation head-on. The Attwood MK2 S800 is a strong candidate, engineered to handle similar pumping demands and install into the same footprint.

This guide walks you through the specifications that matter, how these replacements compare to your original pump, and how to confirm compatibility before you buy. We'll also cover the wiring and hose considerations that often trip up DIY installers, plus a straightforward testing procedure once your new pump is mounted.

Attwood MK2 S800 #5509-7 as a Direct Replacement

The Attwood MK2 S800 represents the modern evolution of the Sahara line and is widely recognized as the most direct successor to the S750. Attwood engineered the Sahara Mk2 series to eliminate air-locks, a persistent problem in older automatic bilge pumps, using a patented X-Air Impeller that ejects trapped air from both the pump and pipework.

The MK2 S800 comes in both 12-volt and 24-volt configurations. For most recreational vessels that originally ran a 12-volt S750, the Attwood Sahara MK2 S800 Bilge Pump 800 GPH 12v Automatic #5508-7 is the logical choice. If your boat uses a 24-volt system, the 24-volt variant #5509-7 is available.

Pump Capacity and Performance

The MK2 S800 delivers 800 gallons per hour, which is a modest 50-GPH increase over the original S750's 750 GPH rating. In real-world terms, this difference is negligible for most vessels, your bilge compartment will drain just as effectively, and the slightly higher capacity actually provides a safety margin if water ingress accelerates during rough weather or if your through-hulls need cleaning.

The real performance advantage lies in how the pump handles air bubbles. Bilge systems often trap air when the water level drops below the intake, which causes the pump to cycle on and off without actually moving water. The X-Air Impeller solves this by actively ejecting air, meaning your pump runs more efficiently and your float switch doesn't exhaust itself with phantom activations.

Attwood's technical documentation on bilge pump performance confirms that the Mk2 design reduces cycling compared to first-generation Sahara models, extending the motor's service life and reducing the strain on your boat's electrical system.

Construction and Corrosion Resistance

Both the original S750 and the MK2 S800 are built for saltwater environments, but the newer model includes upgrades that matter if you run in harsh conditions. The MK2 features a stainless steel shaft and steel-reinforced seals, with permanent magnet motors designed for a cool-running operation even during extended use.

Attwood claims the Mk2 offers 40% better protection against water ingress and electrolysis compared to the Mk1 generation, and 2X better protection than leading competitors. For boat owners storing vessels in salt marshes or operating in brackish water, this corrosion resistance translates to fewer replacement cycles and lower maintenance costs over the pump's lifetime.

The motor housing and impeller are engineered to handle both freshwater and saltwater without degradation, so you can confidently install the MK2 S800 in your vessel regardless of where you dock.

Seachoice 19276 Bilge Pump as an Alternative

One consideration: Seachoice pumps are often positioned as budget-conscious alternatives. While the 19276 is reliable, it lacks the proprietary air-lock elimination technology that the Attwood MK2 brings to the table. If your vessel has a history of air-lock problems or if you operate in conditions where water ingress is frequent, the Attwood option is the stronger choice. For vessels with well-maintained through-hulls and moderate bilge activity, the Seachoice performs adequately at a lower cost point.

Bilge Pump Wiring and Hose Compatibility

Installing a replacement bilge pump means confirming that your vessel's electrical wiring and hose routing will accept the new unit. Most compatibility issues arise here, not from the pump itself.

Voltage and Electrical Requirements

Your boat's electrical system determines whether you need a 12-volt or 24-volt pump. Check your main battery bank and the voltage rating on your existing breaker or switch panel. Mixing voltages causes motor burnout and creates a fire hazard, so this is non-negotiable.

The Attwood MK2 S800 comes in both 12-volt and 24-volt models. If you're replacing a 12-volt S750, order a 12-volt replacement. If you're unsure, consult your boat's electrical schematic or contact a marine electrician before ordering.

Wiring gauge also matters. Bilge pump circuits typically run on 15-amp or 20-amp breakers, and the wire connecting the pump to the battery must be appropriately sized to handle the current without voltage drop. According to American Boat and Yacht Council (ABYC) standards for marine wiring, a 12-volt pump circuit running more than 10 feet should use 10-gauge tinned copper wire. Shorter runs can use 12-gauge. Tinned copper resists corrosion far better than standard copper in the marine environment, so never substitute regular electrical wire.

Float Switch and Automatic Activation

The Attwood MK2 S800 uses a float switch to trigger automatic activation. The switch rests on the water surface and tilts when bilge water rises, closing an electrical contact that energizes the pump motor. When the water level drops, the float descends and the switch opens, shutting the pump off.

Mercury-free float switches are now standard in the industry. Older Sahara S750 units may have used mercury-based switches, which are no longer manufactured due to environmental regulations. If your original pump is old enough to have a mercury switch, replacing it with a modern mercury-free switch is not just an upgrade, it's the right environmental choice.

Attwood Sahara MK2 S800 Bilge Pump 800 GPH 12v Automatic #5508-7 →

The float switch mechanism is sealed to prevent water wicking up the switch wire into the electrical connections. This seal is critical in saltwater applications where corrosion can creep along wet wires. The Attwood MK2 incorporates this protection.

How to Test an Automatic Bilge Pump After Installation

Once your replacement pump is mounted and wired, testing confirms that the float switch activates correctly and the pump moves water as expected. A failed test before you rely on the pump could save your vessel from taking on water during an emergency.

Step 1: Verify Voltage at the Pump Use a multimeter to confirm that the correct voltage (12V or 24V) reaches the pump terminals when the float switch is activated. Set the multimeter to DC voltage, touch the probes to the positive and negative terminals, and manually tilt the float switch upward.

Step 2: Test Manual Activation With the bilge dry, pour water slowly into the compartment and watch the float rise. The pump should activate automatically as the water level climbs. Listen for the motor to spin and feel for vibration at the pump housing.

Step 3: Confirm Water Discharge Once the pump is running, trace the discharge hose to confirm water is flowing out of the vessel, not backing up into the bilge.

Step 4: Test Shut-Off Stop pouring water and allow the float to settle. The pump should shut off automatically as the bilge level drops. If the pump continues running after the bilge is empty, the float switch may be stuck or misaligned.

Step 5: Cycle Test Under Load If you have access to a hose, run bilge water into the compartment several times and verify that the pump activates and shuts off consistently. Erratic cycling or failure to shut off indicates a wiring issue, float switch malfunction, or electrical contact corrosion.

Comparison Table: Sahara S750 Replacement Options

Which Replacement Is Right for Your Vessel

Choosing the Attwood MK2 S800 depends on two factors: your boat's voltage system and whether air-lock prevention is a priority for your specific use case.

Choose the Attwood MK2 S800 if: Your vessel operates in challenging conditions, rough water, frequent water ingress, or extended periods between maintenance. The X-Air Impeller is a genuine engineering advantage that reduces pump cycling and extends motor life. If your original S750 suffered from air-lock problems, the MK2 directly addresses that weakness.

Choose the Seachoice 19276 if: You're replacing a pump that performed reliably in your vessel and you want to minimize cost. The Seachoice is dimensionally matched to the S750, so installation is straightforward. For recreational boats with moderate bilge activity and well-maintained through-hulls, the Seachoice delivers adequate performance without the premium pricing of the Attwood MK2 line.

Verify your voltage before ordering. A 12-volt pump in a 24-volt system burns out immediately. Check your battery bank and electrical panel to confirm which voltage your vessel uses. When in doubt, consult your boat's wiring diagram or ask a marine electrician.

First Choice Marine stocks both the Attwood MK2 S800 in 12-volt and 24-volt configurations, along with the complete Sahara MK2 range including the S500 and S1200 models for vessels that need higher or lower capacity. All Attwood MK2 pumps qualify for free shipping, and our team can help you confirm compatibility with your specific vessel before you order.

Finding a replacement for a discontinued bilge pump doesn't mean compromising on reliability or fit. The Attwood MK2 S800 is a proven solution that restores automatic water removal to your vessel. Test your new pump thoroughly before relying on it, verify your wiring and hose routing, and you'll have restored a critical safety system to your boat.