Groco TH4000W 4" Bronze Thru-Hull Fitting with Nut

Groco

<h3>About Groco: A Century of Marine Innovation</h3><p>Few names in the marine hardware industry carry the weight of experience and craftsmanship that <strong>Groco</strong> does. Short for Gross Mechanical Laboratories, Inc., Groco was founded in 1918 by Angus Roy Gross Sr. — a tinkerer and innovator who started the company in the basement of a Baltimore row house. From those humble beginnings, Angus and his personally trained team built a reputation rooted in precision engineering and an uncompromising commitment to quality that continues to define the brand more than a century later.</p><p>Headquartered in Stevensville, Maryland, Groco has long been the go-to source for boaters and marine professionals who demand components that perform reliably in the demanding saltwater environment. Angus's inventive spirit led to numerous patents across a surprisingly diverse range of products — from carbonating faucets to automotive tail lights — but it was marine hardware where Groco truly found its calling. That same drive to improve and redesign is baked into every product Groco produces today.</p><h3>What Groco Makes</h3><p>Groco's catalog spans a wide range of below-the-waterline and through-hull marine hardware, with two standout categories that have earned particular loyalty among boat owners and shipbuilders alike.</p><p>One of Groco's most trusted product lines is their <a href="/7373-groco-sea-strainers-200906">sea strainers</a>. Designed to protect raw water cooling systems, pumps, and engines from debris and fouling, Groco sea strainers are engineered to handle the rigors of continuous marine use. Whether you're outfitting a small inboard cruiser or a large commercial vessel, the right strainer is an essential safeguard — and Groco's lineup offers solutions across a wide range of flow rates and installation configurations.</p><p>Equally important to any vessel's integrity are reliable <a href="/7373-groco-thru-hull-fittings-201065">thru-hull fittings</a>. These critical components form the sealed connections between a boat's hull and its plumbing systems, and a failure here can have serious consequences. Groco's thru-hull fittings are manufactured to exacting tolerances, using materials suited for long-term exposure to seawater. Boaters and marine builders have trusted Groco's fittings for generations precisely because the stakes are too high to compromise.</p><h3>Why Boaters Choose Groco</h3><ul style="list-style:disc"><li><strong>Over 100 years of marine expertise</strong> — founded in 1918, with deep roots in innovative engineering</li><li><strong>Made in the USA</strong> — headquartered in Stevensville, Maryland, with a tradition of American craftsmanship</li><li><strong>Engineered for longevity</strong> — products are built to withstand the corrosive, high-stress marine environment</li><li><strong>Broad product range</strong> — with nearly 400 products across multiple marine hardware categories</li><li><strong>Trusted by professionals</strong> — used by boat builders, marine mechanics, and serious boaters worldwide</li></ul><p>Whether you're replacing aging hardware on a classic cruiser or speccing out a new build, Groco's marine hardware represents a standard that serious mariners have relied on for over a century.</p>