GROCO 1-1/2" Bronze Extra Long Thru-Hull Fitting w/Nut

The GROCO 1-1/2" Bronze Extra Long Thru-Hull Fitting w/Nut is the through-hull component serious boaters and anglers rely on when fresh or saltwater systems demand reliability below the waterline. Whether you're installing a raw water cooling line, livewell circulation, baitwell overflow, or bilge pump discharge, this extra-long fitting bridges the gap between your cabin sole and transom with precision engineering. Built for the harsh marine environment, it's the type of component that fades into the background until you need to know it will absolutely hold under pressure and corrosion.

Constructed from C83600 bronze—a copper-based alloy prized for its superior corrosion resistance in saltwater and brackish conditions—this fitting resists dezincification and galvanic attack far better than standard brass or steel. The extra-long configuration accommodates thicker hull construction, composite layups, and boats with substantial cabin sole thickness, eliminating the need for adapters or extensions that create potential leak points. The NPSM/NPT combination thread design provides dual compatibility, allowing secure connection to both national pipe straight mechanical (NPSM) and national pipe tapered (NPT) fittings commonly found in marine plumbing and cooling systems. The integral nut ensures a watertight seal without requiring separate hardware sourcing.

This fitting suits fiberglass hull installations, aluminum boats, and even steel vessels operating in both freshwater and saltwater environments. Anglers managing complex livewell systems, tournament boats with multiple through-hulls, and cruising boaters upgrading aging fittings will appreciate the streamlined installation and dependable long-term performance. The 1-1/2" diameter accommodates moderate to high flow applications without excessive pressure drop, making it suitable for raw water intakes and discharge lines. Always verify your existing through-hull diameter and internal plumbing thread type before ordering to ensure seamless compatibility with your current system.