Bilge and Engine Ventilation

[cmezzino]

I had been reading through other threads about this and wanted some clarification. My boat is a '97 Glastron GS 205 (VP 5.7 GSPLKD) I do not see any form of intake ventilation other than the four (4) vents on the rear of the stern that are up underneath the sun deck.

I clearly understand everything I read about how to route the bilge blower and duct work to exhaust fumes. What I don't understand is whether there is a need to run duct work from the remaining 3 vents that are there. Or, because they are for fresh air intake, and they are above the carburetor level, are the vents themselves adequate without ducting.

In addition, I found this product at WalMart and it does fit. It's sewer hose for an RV. Triple Layer vinyl with steel wire. 20 Ft. section for $8 versus $17 for 10 Ft at West M...

Anyone ever use this? Its a tight fit, but it does fit. I'm using a 3" bilge fan. Looking for a reason why it's not acceptable.

https://www.walmart.com/ip/Camco-Sta...-Hose/23636859

 

[Bondo]

Ayuh,..... That hose will work, if yer willin' to fight with it,.....

The intake needs to be low in the bilge, but never in any bilge water,....

The blower, blows out 1 of the vents/ clam-shells, preferable an aft facin' vent,.....

The others are make-up air, 'n passive/ convection vents,....

 

[cmezzino]

Got it. So, if I understand correctly, run at least one intake duct down low in the bilge maybe on the opposite side as the exhaust duct. The other 2 can just be without ducting.

Yes, clamshell is an excellent way to describe those vents! All four are aft as you mention.

Thanks, Bondo!

 

[Bondo]

if I understand correctly, run at least one intake duct down low in the bilge maybe on the opposite side as the exhaust duct.

Nope,.... Backwards,...... Hose from low in the bilge, to the blower, to an aft facin' vent,.....

Leave the other 3 alone,.....

 

[cmezzino]

Ok, yes, that is what I have done. On the one that has the blower, the hose starts out low in the bilge, but above where water level would get. Connects to fan, and then duct runs up and out the vent. Other 3 vents are left alone with no duct work.

 

[wrench 3]

I've never been able to find out why but they want the intake hose below the air intake of the carburetor.

 

[hemi rt]

I've never been able to find out why but they want the intake hose below the air intake of the carburetor.

Because gas fumes are heavier than air so any fumes will collect in the bilge, I think you might think the blower is to push air into the carb but it is to exhaust the fumes out of the boat thus preventing an explosion that is why you are supposed to run the blower for at least 5 minutes prior to starting the motor.

 

[wrench 3]

hemi rt I understand the principal of the blower extracting the fumes. It's the fresh air intake that they wan't below the carb.