3" Moeller Marine Bilge Blower - Engine Compartment Ventilation

Why a Bilge Blower is Important

Gasoline vapors can accumulate in enclosed engine and bilge spaces. Because those vapors are flammable, powered ventilation is an important safety system on gasoline-powered boats with enclosed engine compartments.

Federal recreational-boat requirements specify that a compartment containing a permanently installed gasoline engine with a cranking motor must either be open to the atmosphere or be ventilated by an exhaust blower system.

A bilge blower is therefore not simply a comfort fan. Its purpose is to help exhaust potentially hazardous vapors from the engine compartment.

Where Should the Blower Intake Be Located?

For federally required powered ventilation systems, the blower intake duct is positioned in the lower one-third of the engine compartment while remaining above the normal level of accumulated bilge water.

This helps the system exhaust air from the lower area of the compartment where gasoline vapors may collect.

Matching 3" Blower Hose

3" Heavy-Duty Vinyl Blower Hose - 420-3

Matching 3" ventilation hose for routing air between the blower, intake ducting and exterior ventilation outlet in compatible marine installations.

Keep blower-hose runs as smooth and direct as practical and avoid crushing, severe bends or kinks that can restrict airflow.

View 3" Blower Hose

Matching 3" Blower Hose Clamp

German-Style Hose Clamp - 4-13

Matching clamp for the 3" blower-hose setup.

Pro Marine lists the 4-13 clamp with a 59-82mm / 2.30-3.20" clamping range and 316 stainless-steel construction.

View 4-13 Hose Clamp

3" and 4" Bilge Blower Options

Need a 4" Bilge Blower Instead?

4" Bilge Blower - 5-3715

Larger 4" blower option for compatible marine ventilation systems designed around 4" ducting.

View 4" Bilge Blower

4" Heavy-Duty Vinyl Blower Hose - 420-4

Matching 4" ventilation hose for the 4" blower system.

View 4" Blower Hose

German-Style Hose Clamp - 4-17

Matching clamp for the 4" blower-hose installation.

View 4-17 Hose Clamp

Marine Wiring Supplies

Bilge blowers are electrical components installed in a demanding marine environment. When replacing a blower, inspect the wiring and connections at the same time.

Keep electrical splices secure and protected from moisture, and use properly sized wiring and circuit protection for the blower installation.

Blue Butt Connectors - BBC - 25 Pack

Electrical butt connectors for compatible bilge blower and marine wiring installations.

View Blue Butt Connectors

1/4" Red Heat Shrink - 14R

Red heat-shrink tubing for protecting compatible electrical connections and identifying positive wiring.

View Red Heat Shrink

1/4" Black Heat Shrink - 14B

Black heat-shrink tubing for protecting compatible electrical connections in marine installations.

View Black Heat Shrink

Bilge Blower Installation Tips

• Match the blower diameter to the ventilation hose diameter.
• Use the correct hose clamp for the blower hose.
• Keep ducting as short and direct as practical.
• Avoid crushed hose, tight bends and kinks that restrict airflow.
• Secure the hose so it cannot fall into accumulated bilge water.
• Position the exhaust intake duct low in the compartment where required.
• Keep the intake above the normal level of accumulated bilge water.
• Inspect blower wiring, terminals and splices during installation.
• Confirm that the blower moves air in the intended exhaust direction.
• Test blower operation before starting a gasoline inboard or sterndrive engine.

How Long Should a Bilge Blower Run Before Starting the Engine?

On boats requiring powered engine-compartment ventilation, the required warning instructs operators to run the blower for at least four minutes before engine startup and check the engine-compartment bilge for gasoline vapors.

If you smell gasoline, do not start the engine. Locate the source of the fuel vapor or leak first.

Does an Outboard Boat Need a Bilge Blower?

Bilge blowers are most commonly associated with boats that have enclosed gasoline engine compartments, such as many inboard and sterndrive boats.

A typical outboard engine is located outside the hull rather than inside an enclosed engine compartment, so the ventilation arrangement is different. Always follow the boat manufacturer's original ventilation design.

Can I Replace a 3" Blower with a 4" Blower?

Do not choose a blower based only on physical size. A replacement system should match the boat's required airflow, ducting size and original ventilation design.

If the boat uses a 3" ventilation system, the 5-3710 blower, 420-3 hose and 4-13 clamp form the matching 3" group. For a 4" system, use the corresponding 4" components.

Key Features and Benefits

• 3" marine bilge blower
• Moeller brand
• Aftermarket marine ventilation component
• Designed for compatible engine-compartment ventilation systems
• Matching 3" heavy-duty vinyl blower hose available
• Matching German-style 4-13 clamp available
• 4" blower system also available
• Marine wiring connectors and heat shrink available
• Helps exhaust air and gasoline vapors from compatible enclosed spaces

FAQ

What size is Moeller 5-3710?
Item 5-3710 is a 3" marine bilge blower.

What hose fits this blower?
Use the 420-3 3" Heavy-Duty Vinyl Blower Hose .

Which clamp fits the 3" blower hose?
Use the 4-13 German-Style Hose Clamp .

Why does a gasoline boat need a bilge blower?
A powered exhaust blower helps remove gasoline vapors from compatible enclosed engine compartments before engine startup.

How long should the blower run before starting the engine?
The required safety warning on applicable boats specifies at least four minutes before engine startup, followed by a check for gasoline vapors.

Where should the blower intake hose terminate?
In a federally required powered ventilation system, the intake duct is located in the lower one-third of the compartment and above the normal level of accumulated bilge water.

Do you stock a 4" blower?
Yes. Pro Marine stocks the 5-3715 4" Bilge Blower along with matching 4" hose and clamp.

Do you carry wiring supplies for the blower?
Yes. Pro Marine stocks blue butt connectors , red heat shrink and black heat shrink .

Searchable Terms

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