Attwood Marine Clam Shell Vents

Attwood Marine Clam Shell Vents: Trusted Protection for Your Boat's Hull

When it comes to keeping water, spray, and debris out of your boat's vent holes, wire runs, and hose openings, few solutions are as time-tested as a quality clam shell vent — and few names carry as much weight in the marine world as Attwood Marine. Founded in 1893, Attwood has spent well over a century engineering hardware that boaters can genuinely rely on, and their clam shell vents are a clear reflection of that long-standing commitment to quality.

Built to Withstand the Marine Environment

Attwood's clam shell vents are constructed from 300 series stainless steel, a grade chosen specifically for its corrosion resistance in the demanding saltwater and freshwater environments boats encounter every day. The polished finish not only resists rust and discoloration but also gives the vent a clean, professional appearance on any hull. Whether you're running a small fishing boat or a larger cruiser, the materials hold up where cheaper alternatives quickly fail.

Practical Design, Straightforward Installation

The Attwood clam shell vent (model 66400-3) is engineered with function in mind. It provides a reliable seal and splash protection for vent holes as well as wire and hose openings — a critical detail on any vessel where electrical runs or fuel-system hoses pass through the hull. The large variant covers holes up to 1-1/2" in diameter and accommodates hose or wire up to 9/16" in diameter, while the small variant (66399-3) handles hose or wire up to 7/16" in diameter, making it easy to match the right vent to your specific application.

Installation is equally practical: each vent features three pre-drilled mounting holes sized for #6 fasteners, allowing a secure, watertight fit with minimal effort. Attwood vents are sold in pairs, so you can address port and starboard openings or multiple hatch points in a single purchase.

Meeting Industry Standards

Attwood's marine ventilation products are designed and tested against the highest performance and regulatory standards in the industry, including USCG, ABYC, and CE requirements. This level of compliance matters for safety-conscious boaters who want confidence that their hardware meets recognized benchmarks — not just marketing claims. The clam shell vent also carries a limited 1-year warranty, a further sign of the brand's confidence in its own manufacturing.

A Century of Marine Hardware Excellence

Attwood is widely acknowledged as a leader in innovative deck hardware, setting the industry standard for quality and reliability across a broad catalog that spans ventilation, lighting, fuel systems, bilge pumps, and more. Their clam shell vents represent the same foundational philosophy that has defined the brand since the late 19th century: practical engineering, durable materials, and hardware that simply does its job — season after season, in whatever conditions the water throws at it.

Browse the full selection of Attwood Marine products or explore all available clam shell vents to find the right fit for your vessel.