Attwood Marine Stainless Steel Scupper Valve, SS316, Neoprene Flap, Mirror Finish

Overview

The Attwood Marine Stainless Steel Scupper Valves is a range of barbed stainless steel scupper valves for cockpit, deck, and transom drain installations above the water line. These fittings combine a polished stainless exterior with an internal scupper flap that helps limit backwash when water pushes back toward the drain outlet.

This range covers 1-1/2 in and 2 in hose sizes, giving boat builders and owners a straightforward way to match the valve to existing drain hose and hull thickness. The bodies use Enhanced 316 stainless steel alloy, and the barbed tail gives room for hose clamps at the connection point.

Key features

• Enhanced 316 stainless steel alloy body for drain outlets exposed to spray, washdowns, and saltwater air.
• Scupper flap uses tough neoprene rubber with a molded V that seats into the grooved body to help reduce backwash.
• Concealed, corrosion-proof fasteners keep the outside face clean and reduce exposed hardware around the drain outlet.
• Barbed tail end leaves room for multiple hose clamps, which is useful where drain hose movement and vibration need a secure connection.
• Channel under the flange helps hold a bead of sealant during installation for a cleaner seal at the hull or transom surface.
• Wrench flats or an end notch give the installer a gripping surface so the fitting can be tightened from inside the hull.
• Intended for installation above the water line only.

Variants

This product is offered in two hose-size configurations for matching different scupper drain runs.

The hose size, thread size, installation hole saw size, and maximum hull thickness change between the two variants. The scupper flap construction, stainless steel valve body, and above-waterline installation requirement remain consistent across these barbed scupper valve models.

• 66553-1: 1-1/2 in hose size. This version uses 1-1/2 in NPSM threads, a 2 in installation hole saw size, and supports up to 3 in maximum hull thickness.
• 66555-1: 2 in hose size. This version uses 2 in NPSM threads, a 2-1/2 in installation hole saw size, and supports up to 2 in maximum hull thickness.

Installation and fit

Match the valve to the inside diameter of the drain hose already on the boat, then confirm the hole saw size and available hull thickness before cutting or replacing an existing fitting. The 1-1/2 in version has a 3 in flange outside diameter and 5-1/2 in total length, while the 2 in version has a 3-5/8 in flange outside diameter and 4-1/2 in total length.

Because this is a scupper valve, placement matters. It belongs in an above-waterline drain outlet where the flap can help with backwash while still allowing deck or cockpit water to leave the boat. The barbed outlet should be paired with hose of the correct size and clamps suitable for the hose and installation environment.

Use on board

These valves are a good match for owners, yards, and builders working on cockpit drains, deck drains, and transom scupper outlets where a stainless exterior is preferred over plastic. They make sense on fishing boats, center consoles, cruisers, and other vessels where drain outlets see spray, sun, and regular washdowns.

Maintenance and care

Rinse the exterior with fresh water after saltwater use and inspect the flap during routine cleaning. A flap that is blocked by debris, marine growth, or hardened residue may not seat cleanly, so keeping the scupper area clear helps the valve drain properly and limit backwash as intended.

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.