Shields Marine Vinylvent Ducting Hose – Series 400/402, 4" Black (Bulk Roll)

Marine-Grade Bilge Ventilation Hose – 4" UV-Resistant PVC with Anodized Wire Helix, Black

The Shields Marine Series 400/402 Vinylvent is a flexible PVC ducting hose reinforced with an anodized wire helix for shape retention and crush resistance. Designed for marine bilge ventilation, it safely channels engine compartment gases and bilge fumes away from enclosed spaces on powerboats and inboard-powered vessels.

The 4" interior diameter suits larger blower systems and higher-capacity ventilation runs found on larger inboard and sterndrive vessels. The anodized wire helix maintains the hose’s round profile through tight bends and routing around obstacles, while the PVC construction resists UV degradation and ozone exposure for long service life. The black finish blends cleanly into engine compartments and bilge spaces. This listing is for a 4" interior diameter bulk roll.

Key Features

• PVC construction reinforced with anodized wire helix for shape retention and crush resistance
• Resistant to UV, ozone, and weathering
• Flexible and easy to route through tight engine compartment spaces
• Black finish — clean, professional appearance in bilge and engine compartment installations
• 4" interior diameter
• Bulk roll — cut to length as needed
• Series 400/402

Primary Application

Designed for venting bilge fumes and engine compartment gases on powerboats and inboard-powered vessels. Suitable for use with standard 4" marine blower systems. Not intended for use as a fuel line, water line, or exhaust hose.

Also Available in This Series

• Shields Vinylvent Series 400/402 – 3" Black, Bulk Roll
• Shields Vinylvent Series 400/402 – 3" Black, 3 ft. Section
• Shields Vinylvent Series 400/402 – 3" White, Bulk Roll
• Shields Vinylvent Series 400/402 – 3" White, 3 ft. Section

Parts Desk Insights

Best Use Case: The 4" black bulk roll is the right recommendation for professional installers and marine yards doing full ventilation system builds or replacements on larger inboard or sterndrive vessels where 4" blower systems are specified. The 4" diameter is less common than 3" but is required on some larger-displacement engines and twin-engine installations where higher airflow volume is needed. Always confirm the customer’s blower inlet/outlet diameter before selling — mixing 3" and 4" components in the same run will cause fitment issues.

4" vs. 3" Diameter: Most production powerboats use 3" blower systems. The 4" diameter is typically found on larger custom builds, commercial vessels, or high-displacement inboard engines. If a customer is unsure of their hose diameter, have them measure the existing hose interior or check the blower motor inlet size before ordering.

Black vs. White: Functionally identical — colour choice is purely aesthetic. Black is generally preferred in engine compartments for a professional finish and hides grime better over time. White is easier to inspect for cracks during routine maintenance.

Cutting Tip: Score around the circumference with a utility knife and bend to snap the wire, then trim the vinyl cleanly. Secure with stainless hose clamps at each end.