Attwood 1423-5 Louvered Bilge Vent, Matte Black ABS

If you've ever gone looking for the vent that sits flush on a boat's hull side and lets the engine compartment or bilge breathe, this is it. The Attwood 1423-5 is the louvered vent face that pairs with Attwood's 1341 and 1342 collector boxes. Matte black, molded from ABS plastic, and shipped with its own fasteners. It's the part you see from the outside. The collector box is the part hidden behind it, and that's sold separately.

Here's how the system works. The collector box mounts inside the hull and gives you a clean hose connection. The 1341 box handles a 3 inch ducting system, and the 1342 box handles a 4 inch system. This vent is the exterior grille that fastens over the opening and keeps the weather out while the air keeps moving. Attwood builds these to install as a complete unit, so you're mounting one piece to the hull rather than fussing with a stack of loose trim rings.

The louvers are canted, angled down and out, so rain and spray get deflected instead of running straight into the compartment. That matters on a boat that lives on a mooring or trailers down the highway in the rain. Water finds every opening it can, and a well-angled louver is your first line of defense. The matte black finish keeps it low-key against a dark hull or a rubrail, and ABS holds up to sun and salt without the chalky fade you get from cheaper plastics.

This vent is designed to work as either an intake or an exhaust, so you can run a matched pair, one drawing fresh air in and one letting warm air out. It's built to meet the ABYC H-2 cross sectional area requirement, which is the standard that governs how much open venting area a gasoline engine compartment needs to clear fumes safely. If you're rigging or repowering a gas boat, that's the spec your surveyor and your insurance company care about. Getting the vent area right isn't a nicety. It's how you keep fuel vapor from collecting where it shouldn't.

Why does the airflow area matter so much? A gasoline inboard or sterndrive lives in a closed box, and gas fumes are heavier than air, so they pool in the bilge if nothing moves them. The louvered vent, the collector box, and the blower hose work together to pull that air out and draw fresh air in. Undersize the venting and you're fighting the code and the physics both. Size it right with a matched 1341 or 1342 box and this vent does its share of the job.

Who's this for? Boat builders finishing a hull, riggers plumbing a new blower system, and owners replacing a cracked or sun-baked vent that's been on the boat for a decade. If your old louvered vent is chalky, brittle, or missing a corner, swapping in a fresh one is a quick job. Pull the old fasteners, clean the mounting surface, set the new vent, and drive the included screws. A bead of marine sealant behind the flange and you're done.

Maintenance is about as simple as it gets. Give the louvers a rinse when you wash the boat so salt and grime don't build up in the slots and choke the airflow. Every so often, check that the fasteners are still snug and the sealant behind the flange hasn't let go. That's the whole list. There's no motor, no filter, no moving part to wear out. It's a molded grille doing an honest job, and the plastic shrugs off UV and spray better than the painted metal vents it often replaces.

A couple of honest notes. This is the vent only. If you don't already have a 1341 or 1342 collector box in the hull, you'll need to add one to complete the system, and you'll want to match the box to your hose size, 3 inch or 4 inch. And because it's a hull-side fitting, take a minute to bed it properly. Any opening through the topsides deserves sealant and snug, evenly driven fasteners so you don't chase a drip later. Do it once, do it right, and this vent moves air quietly for years.