Attwood's marine ventilation components include passive hull vents, collector boxes and powered inline blowers. Choosing parts by their exact connection size matters: the three-inch and four-inch duct systems use different collectors and fan housings. Compare the part numbers below to build or service a suitable ventilation arrangement.
Three parts of a marine ventilation system
The louvered opening admits or exhausts air. Its shape and mounting hole must match the hull.
A shaped fitting connects the vent to one or two ventilation ducts of the specified diameter.
An inline 12V fan moves air through appropriate ventilation ducting. Match its diameter and electrical rating.
Attwood 3-inch and 4-inch bilge ventilation comparison
The 1494 louvers can use a 1341 collector with two three-inch hoses or a 1342 collector with one four-inch hose. The 1495-1 works with 1345 for a three-inch system. The 1438F1 modular centre section uses the 1348 four-inch system with matching end sections.
| Part number | Component | Duct diameter | Matching system / specification |
|---|---|---|---|
| 1494A1 | Black louvered vent | 3 or 4 in | 1341 for two 3-in ducts; 1342 for one 4-in duct |
| 1494A5 | Black louvered vent | 3 or 4 in | 1341 for two 3-in ducts; 1342 for one 4-in duct |
| 1495-1 | Off-white louvered vent | 3 in | 1345 collector for two 3-in ducts |
| 1438F1 | White modular centre vent | 4 in | 1348 collector; 1439F1 end pieces for complete modular vent |
| 1733-4 | Turbo 3000 inline blower | 3 in | 12 V DC; 120 CFM open flow at nominal 12 V |
| 1749-4 | Turbo 4000 inline blower | 4 in | 12 V DC; 200 CFM open flow at nominal 12 V |
Collector boxes, modular end sections, hose and installation hardware are separate components unless a specific product's listed package contents say otherwise.
Attwood Turbo bilge blower airflow ratings
At nominal 12V, Attwood lists 120 CFM open flow for the Turbo 3000 and 200 CFM for Turbo 4000. At 13.6V, open-flow figures rise to 145 and 230 CFM respectively. Figures measured in an installed duct system are lower.
Attwood's reference system with three feet of duct, a 90-degree bend, a collector and louver produces lower airflow than an unobstructed blower. Actual performance depends on the complete installation. Match duct size before choosing the blower.
Ventilation fitting and electrical checks
Confirm the required intake and exhaust locations, collector box, duct run, fastening arrangement and power supply against the vessel manufacturer's instructions. Where a powered blower is required for an engine compartment, follow applicable marine ignition-protection and ventilation standards.
Blowers and passive vents serve different functions. Do not use an undersized fan or incompatible collector in place of an approved boat ventilation system.
Attwood vent faces and 12V inline bilge blowers
Select the correct component below for current product details and availability.
Attwood 1494A1
Black ABS louver that uses the corresponding collector box, chosen by duct diameter.
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Attwood 1494A5
Another packaging form of the black 1494 louvered vent, with the same collector family.
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Attwood 1495-1
Off-white louvered face designed for the Attwood 1345 three-inch collector arrangement.
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Attwood 1438F1
Interlocking white centre section for a four-inch modular system; not a complete assembled vent by itself.
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Attwood 1733-4
Water-resistant 12V inline blower for three-inch ventilation hose; nominal 120-CFM open-flow specification.
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Attwood 1749-4
Water-resistant 12V inline blower for four-inch hose; nominal 200-CFM open-flow specification.
View product details and availabilityRelated marine bilge parts
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