Attwood Marine S3 Series Automatic Bilge Switch, 12V, 15A, Electronic Sensing
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Overview
The Attwood Marine 4801-7 is a 12V automatic bilge switch that uses electronic sensing to activate a bilge pump when water reaches the switch and shut the pump off once the water is cleared. It is rated for pump loads up to 15 amps and comes with a 36 inch wire lead, so it fits many 12V bilge pump circuits where you want automatic operation without relying on a mechanical float switch.
This is the switch only, not the pump. Because it uses solid-state sensing and has no moving parts, it avoids the sticking and wear that can show up with float-style switches over time. The sealed electronics, chemical-resistant housing, and stainless steel components make sense in bilge spaces where water, foam, sludge, and fuel or oil residue are part of real use on board.
Mounting is flexible enough for tight bilge layouts. The switch can be installed on the bilge floor, on a stringer wall, or alongside a compatible pump basket, which helps when you are replacing an older switch and want to keep the sensing point low in the hull.
Key features
- 12V automatic bilge switch for pump circuits up to 15 amps
- Electronic sensing reads bilge water and helps reduce nuisance cycling from sloshing water, foam, and residue in the bilge
- No moving parts, so there is nothing to jam, crack, or wear like a mechanical float mechanism
- Sealed electronics with a chemical-resistant housing and stainless steel components
- 36 inch wire lead for routing in common bilge installations
- Mounts on the bilge floor, on a stringer wall, or alongside a compatible pump basket without extra brackets
- Backed by a 5 year warranty
Installation and setup
On a 12V boat, the main fit check is pump current draw. This switch is built for pumps that stay within the 15 amp limit, so it is important to confirm the pump load before wiring it into an automatic bilge circuit. The 36 inch lead gives enough reach for many compact bilge compartments without forcing splices right at the switch body.
The mounting choices are useful when the lowest part of the bilge is narrow or crowded. Keeping the switch in a spot where water collects naturally will help it respond as intended, while wall or basket mounting can make service access easier on boats where the bilge floor is hard to reach.
Compatibility and fit
This switch is a good match for owners replacing a worn float switch or adding automatic control to a compatible 12V bilge pump. It also works well where the bilge sees motion, foam, or dirty water that can make some mechanical switches cycle more often than they should. If your boat uses a 24V bilge circuit or a pump that pulls more than 15 amps, this is not the right version.
Use on board
This suits boats that spend time at the dock, on a mooring, or on a trailer between trips and still need the bilge protected automatically. It also makes sense for owners who want a cleaner switch setup in the bilge with fewer moving parts to service over time.
Shipping
We ship worldwide from the United States. Rates are calculated at checkout based on destination and package weight. Some items include free shipping, which will show automatically. Not every product is eligible for international shipping; checkout will confirm eligibility. We do not ship to PO Boxes except through USPS, and not all packages qualify.
Processing and dispatch
Most orders are verified, packed, and handed to the carrier within 1 to 2 business days. Some products may need extra handling time or ship directly from the manufacturer. For certain international orders, inventory transfers between warehouses may add time. If any delay is expected, we will let you know the dispatch date.
Delivery and tracking
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Duties, taxes, and support
International customers are responsible for any customs duties, taxes, and fees charged by the destination country. If these charges are refused and a shipment returns to us, the carrier’s return cost and any re-entry customs fees will be deducted from the refund. If your order is late or you need help, contact cs@qualityboatparts.com and we will assist you.
Quality Boat Parts is a reseller. Many items include a manufacturer’s warranty, and all warranty service is handled directly by the manufacturer. We do not manage or administer warranty claims on behalf of customers.
Warranty terms, coverage, and duration are set by each manufacturer. Issues involving defects, repairs, or replacements must be addressed with the manufacturer’s support team. When available, the warranty period is listed on the product page. If it is not shown, contact us or the manufacturer for details before purchasing.
To start a claim, the customer must contact the manufacturer and follow their process. Keep your proof of purchase and original packaging, and register the product if the manufacturer requires it, as these are often needed for warranty service.
We are happy to help you find the right contact or documentation, but we cannot decide outcomes or intervene in claim resolutions. For guidance, email cs@qualityboatparts.com.