GROCO 3" Bronze High Speed Thru-Hull Fitting w/Nut

The GROCO 3" Bronze High Speed Thru-Hull Fitting w/Nut is engineered for serious cruisers and fishing vessels where raw water flow and reliability matter. Whether you're upgrading a cooling system, installing a livewell, or adding through-deck plumbing on a saltwater boat, this 3-inch thru-hull delivers the high-volume water passage you need without the drag penalty of standard fittings. Built by GROCO—a trusted name in marine hardware for decades—this fitting handles the demanding conditions anglers and boaters face in coastal and offshore environments.

Machined from C83600 bronze, this high-speed thru-hull fitting combines superior corrosion resistance with exceptional flow capacity compared to conventional designs. The NPSM/NPT combination thread accommodates both tapered and straight-thread components, giving you flexibility in system plumbing without adapters. The streamlined bore profile reduces turbulence and pressure drop, a critical advantage when cooling engines or running high-capacity livewell systems. At just 1 pound and engineered to minimize hydrodynamic drag, this fitting won't compromise hull efficiency or speed.

Installation is straightforward: the included nut secures the fitting through the hull, with bronze construction guaranteeing longevity in salt and fresh water alike. This fitting is ideal for 3-inch port applications on center consoles, cruising yachts, and fishing boats where engine cooling, raw water systems, or livewell circulation demand reliable, high-performance through-deck plumbing. Anglers who depend on bait tanks and serious cruisers who run continuous cooling systems will appreciate the reduced maintenance and proven durability GROCO bronze fittings deliver. Verify your existing 3-inch port size and thread type before ordering to ensure seamless installation.