Overview

The Attwood Marine 66400-1 is a clam shell vent in stainless steel for larger exterior vent holes and for wire or hose pass-throughs that need splash cover on a boat. It uses 300 series stainless steel and mounts with three holes for #6 fasteners, which gives it a clean fit on exposed exterior surfaces.

This style works well where you want to shield an opening without adding a bulky fitting. The shell profile helps deflect spray and washdown, while the stainless finish suits visible mounting points on hull sides, cockpit liners, transoms, and cabin sides.

Key features

• Large clam shell format for exterior vent holes and for wire or hose openings that need a splash cover
• 300 series stainless steel body for better resistance to corrosion in saltwater use
• Three mounting holes sized for #6 fasteners
• Low-profile cover that keeps the opening protected without taking much space on the mounting surface
• Useful for refit work when replacing worn plastic or stainless clam shell covers on exposed areas of the boat

Installation and fit

Check the size of the opening, the available flat mounting area, and the fastener spacing before drilling or replacing an existing cover. This vent is best installed with the opening facing away from direct spray so the shell can do its job as a splash cover.

For cable or hose pass-through use, make sure the run behind the panel has enough clearance and does not force a tight bend right under the cover. On older boats, it is worth comparing the footprint against the existing hardware because clam shell vents can look similar while using a different mounting pattern.

Use on board

This part suits owners who need a straightforward exterior cover for a vent opening or a small hose or wire exit, especially on center consoles, fishing boats, cruisers, and sailboats where deck and hull hardware is exposed to sun, salt, and vibration. It is a sensible match when you want a stainless finish that blends with other exterior hardware and keeps the installation looking tidy.