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Bilge ventilation not working properly

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nick williamson

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"hello all. since you all wer

"hello all. since you all were so much help last time, i have another problem. i have an 86 four winns 170 horizon. it has the two vent plates, one on the port side and one on the starboard side. the starboard side vent is not even hooked up. it looks like two hoses are supposed to connect there. there is one hose that is connected, however it is cut.
on the port side vent plate there are two hoses running to it. it appears to be sucking air from one of the holes and blowing it out under the motor and the other hose on that side doesn't seem to be doing anything.
it anyone can help i would appriciate it and a diagram would be awesome. i have looked everywhere on the web and can't find one. thanks a lot"
 
"often 1 scoop is aimed forwar

"often 1 scoop is aimed forward so when you are cruising air gets forced in. On my Bayliner, they both point bckwards because that probably looked sportier

As long as the blower is moving air out, new air will come in. The engine moves a fair bit too."
 
"thanks for the help. i was c

"thanks for the help. i was curious, is there supposed to be 2 pumps or just the one. if there is just one pump how does all 4 hoses hook up to it. i don't understand how one pump will suck air in the bilge area and also blow it outside while sucking the air out of the bilge area."
 
"next time you are drinking th

"next time you are drinking through a straw, stop while liquid is in the straw and quickly put your thumb over the top of the straw. The liquid will not run out and that is because your thumb wont let air in to replace it. Once you remove your thumb and the liquid runs out, air comes in the top to replace it. This is also used to siphon fluids.

So, if one fan blows air out of a compartment - you don't need another to put new air in. It will fill the void naturally. The atmosphere of our planet is actually pressurized to 14.7 psi (at sea level) and so you have pressure all around doing this sort of work wherever a void exists."
 
"Maybe this will help. The bl

"Maybe this will help. The blower would be in the exhaust duct. Run duct hose from a low point in the bilge, to the blower, then to the exhaust cowl. As Hystat said, the intake cowl should face forward and the exhaust cowl rearward. This promotes air flow while boat is traveling.
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VENTILATION (Fuel Vapors)
Any boat using a fuel with a flashpoint of 110 (degrees) or less (gasoline, but not diesel) that has any enclosed engine or fuel tank spaces (not open to the atmosphere) must have an efficient ventilation system to disperse explosive gases. Natural ventilation consists of at least two ventilation ducts fitted with cowls or their equivalent. At least one exhaust duct extending to the lower portion of the bilge and at least one intake (supply) duct extending to a point midway to the bilge or at least below the level of the carburetor air intake is required. Boats built after July 31, 1980 are required to have powered ventilation (exhaust blower) for engine compartments that are not open to the atmosphere. Such boats are required to display a warning label such as this:

“Warning - gasoline vapors can explode. Before starting engine operate blower for 4 minutes and check engine compartment bilge for gasoline vapors. Gas vapors contained in an enclosed space make a boat a potential bomb waiting to go off!”"
 
thanks a lot for the help guys

thanks a lot for the help guys. i really appriciate it.
 
"Wow, this is a great thread.

"Wow, this is a great thread. I'm e-mailing it to myself so I can have it for reference. The duct hoses on mine were kinda messed up, and I could never find any reference to make them right. This is perfect. Thanks!"
 
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