GROCO 3/4" Bronze High Speed Thru-Hull Fitting w/Nut

The GROCO 3/4" Bronze High Speed Thru-Hull Fitting with Nut is a marine-grade through-hull fitting engineered to maximize water flow while minimizing drag on through-hull applications. Manufactured from C83600 bronze—a marine-proven alloy—this fitting delivers the corrosion resistance and durability required for saltwater and freshwater hull penetrations. The high-speed design sets it apart from standard thru-hull fittings by optimizing internal geometry for faster flow rates, a critical advantage when cooling systems, raw-water intakes, or drainage lines demand reduced pressure drop.

The 3/4" diameter with NPSM/NPT combination threading provides flexibility for both straight and tapered pipe connections, allowing integration with existing marine plumbing infrastructure. Bronze construction resists galvanic corrosion in saltwater environments far better than stainless steel alternatives in certain applications, and the included nut simplifies installation through the hull. The compact footprint and robust bronze body mean this fitting tolerates the vibration, thermal cycling, and pressure variations typical of marine duty without degradation or leakage.

This fitting is essential for boat builders, liveaboard owners, and marine maintenance professionals managing cooling system upgrades, bilge pump installations, or raw-water through-hull replacements. Weekend cruisers and offshore anglers alike benefit from the improved flow efficiency, which reduces strain on circulation pumps and lowers operating temperatures on systems running in warm or shallow water. Whether you're servicing a sailboat, center console, trawler, or commercial workboat, the GROCO high-speed design ensures reliable performance where standard fittings fall short.