GROCO 1-1/4" Bronze Extra Long Thru-Hull Fitting w/Nut

The GROCO 1-1/4" Bronze Extra Long Thru-Hull Fitting w/Nut is an essential through-hull penetration for any serious vessel owner running water systems, cooling loops, or drainage applications. If you've spent years on the water, you know that thru-hull fittings take constant abuse from saltwater corrosion, thermal cycling, and vibration—and failure below the waterline is simply not an option. This extra-long design accommodates thicker hull materials and multiple internal plumbing configurations without compromising structural integrity.

Machined from C83600 bronze—a marine-grade alloy specifically formulated for saltwater resistance—the GROCO fitting delivers superior corrosion protection compared to standard brass or cast materials. The extra-long NPSM/NPT combination thread design allows flexibility in interior plumbing connections, accommodating both national pipe thread and tapered configurations without adapters. Bronze resists dezincification and maintains structural strength across decades of service, even in harsh offshore environments where aluminum and inferior alloys deteriorate within years.

This 1-1/4" fitting suits vessels with composite or thick fiberglass hulls, commercial fishing boats, and displacement cruisers requiring maximum thread engagement for watertight seals. The included nut ensures secure installation against the hull exterior, while the extra-long body prevents hose-clamp contact with the fitting shoulder—a critical detail that prevents micro-movement and future leaks. Whether replacing failed fittings on a long-range cruiser or building out a new system, the GROCO thru-hull fitting for sale here represents the proven choice of captains and marine technicians who refuse to compromise on below-waterline reliability. Specifications match MPN THXL-1250-W for compatibility verification.