Forespar Marelon Full-Flow Seacock & 1/2" Mushroom Through-Hull

The Forespar Marelon Full-Flow Seacock & 1/2" Mushroom Through-Hull is a complete integrated system engineered for serious boaters who demand reliability below the waterline. This two-part assembly pairs a Marelon valve with a precision-matched mushroom head through-hull fitting, eliminating the compatibility issues that plague mismatched components. Whether you're outfitting a new vessel, replacing a corroded bronze seacock, or upgrading an older cooling system intake, this full-flow design keeps water flowing freely while maintaining absolute shutoff capability when you need it.

Built with Marelon composite material instead of traditional bronze, this seacock eliminates galvanic corrosion issues that weaken traditional metal fittings over time—a critical advantage in salt water applications. The full-flow design minimizes turbulence and pressure drop, allowing your engine cooling system or raw-water intake to operate at peak efficiency without the restrictions of traditional ball or gate valves. The 1/2" mushroom through-hull features heavy-duty buttress-type threading that resists loosening from vibration and engine stress, ensuring the fitting stays seated and watertight through years of operation.

This system is ideal for engine cooling intakes, head ventilation loops, and any through-hull application where corrosion resistance and smooth flow are priorities. The pre-matched pairing eliminates guesswork during installation—the valve and through-hull are engineered to work together seamlessly, reducing the risk of leaks from mismatched thread pitches or sealing surfaces. Installation requires basic through-hull preparation and fits standard 1/2" applications; refer to your vessel's schematic to confirm compatibility with existing piping and deck penetrations.