GROCO 1.25-Inch Bronze High-Speed Thru-Hull Fitting

The GROCO HSTH-1250-W is a high-speed thru-hull intended for intake systems that benefit from water being presented to the opening while the boat is moving. Its streamlined high-speed exterior profile is designed to increase flow while limiting drag compared with a conventional scoop. A retaining nut is included for a secure through-hull installation. That makes the fitting useful for applications such as engine cooling, livewell circulation, or other equipment whose intake must remain supplied underway.

The HSTH-1250-W uses C83600 bronze and a combination NPSM/NPT threaded body for connection to compatible marine plumbing. The installer should still match the fitting to the pump or engine's actual flow requirements rather than selecting a scoop solely by physical size. The external pickup geometry is integral to the fitting, so the water-facing orientation matters during installation. Compared with building an intake from a plain thru-hull plus a separate scoop, the combined design keeps the hull-side hardware more compact.

• Combination NPSM/NPT threaded connection
• High-speed intake geometry
• Designed for moving-water intake service
• Retaining nut included for installation

Orient the HSTH-1250-W correctly to the direction of travel before drilling or bedding the fitting, and verify that the inside plumbing has a clear path to the intake equipment. Support the connected hose or valve so hull movement and vibration do not work against the penetration. After launch, inspect the fitting from inside the vessel and confirm the connected system receives water normally at both idle and operating speed. For other intake fittings, hull strainers, and drain components, browse Thru-Hulls & Drains.