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Gasexhaust fumes do they rise or sink

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rich_b

Contributing Member
"redoing my bilge blower tubes

"redoing my bilge blower tubes.where do they go.22ft, inboard,165hp straight 6cyl.i have a incoming vent on each side of the boats transom that turns into a tube that lays on the floor on each side of the motor.i have another tube that lays on the floor on one side of the motor that goes to the blower and is vented out the center of the transom.it doesnt seem right to me.i have a 71 searay srv220.i want to redo blower and tubes but dont know where to route tubes to.should i add more blowers-should i have a incoming and out going blower.please help cant stand the smell no more.what do the exhaust/gas fumes do rise or sink.thank you rich"
 
The USCG regulations CFR 183.6

The USCG regulations CFR 183.6 covers ventilation of gas powered vessels. You need a powered EXHAUST blower with the intake in the lower one third of the bilge but abovethe bilge water level.

The blower must be able to exhaust the compartment air volume and that more than one blower may be used to meet the regulation.

The purpose of the system is to remove gas vapors that are heavier then air and will accumulate in the lower part of the bilge.
 
"Rich:

EJ has given you the

"Rich:

EJ has given you the straight facts. When I rebuilt my boat, it had a 3" blower installed per CG regs. It has an intake on one side and the exhaust on the other. The inlet grille faces the bow and the outlet faces the stern.

There was one 3" inlet and exhaust opening used on each side. It also had one closed off on each side. I changed the outlet side to a single 4" blower and just added another 3" hose on the inlet that I hang over the carb. for fresh air. One 3" inlet hose still goes to the bilge and the 4" outlet pulls fumes from the bilge. Your blower should run all the time. Go look at some new boats and see how they are installed."
 
If you have heavy exhaust fume

If you have heavy exhaust fumes in the bilge you may have an exhaust leak. The blower should draw the exhaust out. Install 2 blowers; one per CG regs. and one that draws air from above the engine. Also install another air inlet. You can use elbow inlet and outlet vents that draw and vent from the top of the stern.
 
"[b]"what do the exhaust/g

""what do the exhaust/gas fumes do rise or sink."

Ayuh,.....

They Sink......."
 
"Station wagon effect"

"Station wagon effect" will draw the fumes into the boat even as you're running along. I hope you resolve this.

Jeff
 
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