Attwood 3873-1 Thru-Hull Connector 3/4 in Hose White

The Attwood 3873-1 thru-hull connector is one of those simple parts that quietly keeps a boat working. It's a white polypropylene fitting that gives a 3/4 inch hose a clean, sealed path out through the hull or transom. No moving parts, nothing to corrode, nothing to overthink. You pass it through a drilled hole, bed the flange in sealant, clamp your hose to the barb, and you're done.

What makes it worth having in the parts bin is the material. It's molded polypropylene, not brass or chrome-plated metal. On a boat that matters more than it sounds. Metal thru-hull fittings look great on day one, but after a couple of seasons in salt water they pit, they corrode, and the threaded ones tend to seize so hard you end up cutting them out. Polypropylene doesn't do any of that. It shrugs off salt, UV, and the kind of chemistry that lives in a bilge or a livewell. The white color blends in with most gelcoat and painted hulls instead of standing out like a sore thumb.

We reach for a fitting like this on all the usual jobs. Livewell and baitwell drains. Bilge pump discharge lines. Aerator overflow. Deck and cockpit drains. Washdown pump returns. Anywhere a 3/4 inch hose needs to get from the inside of the boat to the outside without leaking, this is the part that does it. If you're plumbing a new livewell or chasing down a tired old fitting that finally cracked, dropping one of these in is an afternoon job at most. Keep the barb pointed where you want the water to go and you're halfway there.

The dimensions are straightforward. The barbed stem fits 3/4 inch hose and runs 3-1/4 inches long, which gives you enough length to pass through hull or transom material up to 1-1/4 inch thick. The flange is 1-3/4 inches in diameter, so it seats flat and gives you a solid face to bed in sealant. That's a common size for drain and discharge work, and it covers the vast majority of small-boat plumbing you'll run into. Measure your hull thickness at the mounting spot before you drill, and make sure the stem has room to clear on the inside.

A couple of install notes from experience. First, bed the flange in a good marine-grade sealant and snug your hose with a stainless clamp. Those two steps are what separate a dry bilge from a slow mystery leak. Second, think about where this fitting lives relative to the waterline. A straight polypropylene connector like this is meant for above-waterline work, think livewell overflow, bilge discharge, washdown returns, the stuff that sits up out of the water when the boat's at rest. If you need a pass-through below the waterline, that's seacock territory and you'll want a proper seacock-rated setup instead. When you're not sure, mount it high.

One more thing worth mentioning. A 3/4 inch line is the common size for a lot of small bilge pumps, livewell aerator kits, and washdown setups, so this connector drops right into gear you probably already own. Match the hose to the pump outlet, run it to this fitting, and you've got a tidy discharge path. Simple, reliable, and the kind of part that just works.

It ships as a single connector in bulk packaging, so you're paying for the part and not a fancy blister pack. That's how most rigging shops want to buy this stuff anyway. Keep a couple on the shelf. Thru-hull fittings are one of those parts you never think about until one cracks, and when that happens you want the replacement in hand, not three days out. For the money, the Attwood 3873-1 is an easy call.