Groco Thru-Hull Fittings
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When it comes to below-the-waterline integrity, Groco has built a reputation for manufacturing some of the most reliable thru-hull fittings in the marine industry. Their comprehensive line of bronze thru-hull fittings combines time-tested materials with innovative design features that deliver both safety and performance for vessels of all sizes.
Premium Bronze Construction and UL Certification
Groco thru-hull fittings are constructed from C83600 bronze and carry UL 647B listing, meeting stringent safety standards for marine applications. For larger applications, the 4-inch and 5-inch sizes utilize C84400 bronze, providing enhanced strength and corrosion resistance. This commitment to premium bronze alloys ensures decades of reliable service in harsh saltwater environments, making Groco fittings a trusted choice for both recreational and commercial marine installations.
Versatile Threading and Enhanced Flow Design
One of Groco's standout innovations is their NPSM/NPT combination thread design, which provides exceptional installation flexibility. The design allows for increased flow compared to standard thru hulls, optimizing system performance for everything from raw water intakes to livewell circulation. This engineering approach means fewer restrictions and better flow rates, particularly important for high-volume applications like engine cooling systems and large bilge pumps.
Comprehensive Product Range
Groco's thru-hull fitting lineup spans from 1/2-inch to 5-inch sizes, accommodating virtually any marine plumbing requirement. Their TH Series represents the core product line, available with or without retaining nuts depending on installation needs. Beyond standard threaded fittings, Groco also manufactures mushroom head barbed models ideal for scupper, sink drain and bilge pump overboard discharge, plus specialized flush-mount options for dripless shaft seal systems and other applications requiring a smooth interior profile.
Why Marine Professionals Choose Groco
Groco's decades of specialization in marine plumbing components means their thru-hull fittings incorporate lessons learned from countless installations worldwide. The availability of both BSPP and NPT thread configurations accommodates international vessel standards, while the included flanged retaining nuts ensure secure mounting through hull thicknesses. Whether you're performing routine maintenance, upgrading an older system, or outfitting a new build, Groco provides the quality and variety that professional riggers and DIY boaters alike depend on for critical below-waterline penetrations.