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Bilge blower thoughts please

R

realcaptron

Regular Contributor
Hi gang. So this topic regards my 1976 Jeffries sportfisher with twin 454s. For those who may not know, Jeffries was a local legend builder in southern California in the 1960s thru early 80s. They built county lifeguard boats and harbor patrol boats as,well as pleasure craft. I mention this to illustrate They were a trusted and knowledgeable builder.
So as to the topic of blowers...my boat has 4 louvered vents (2 forward engine room port and starboard, and 2 in the aft corners, one each side. They ALL installed with vents pointing aft. They each vent into tunnels that enter the engine room about 1/2 way down into the compartment. The forward starboard vent has an exhausting powered squirrel cage blower that I run pretty much constantly.
But I was concerned that there was no powered ventilation near the port engine, so I am installing a continuous duty in line blower over there positioned to EXHAUST. I will also upgrade the starboard blower to match the port side, also EXHAUSTING.
So that's my question...am I right to have an EXHAUSTING blower on each side, while the aft corner vents will still provide natural ventilation? Or should I have one of them pulling air in?
..
 
engine room blowers should be called engine room suckers, you need to pull fumes out of the bilge not dilute the fumes with air blowing into the engine compartment.
 
Honestly the vent direction doesn't really matter, it's all about low vs high pressure. Remember the Pontiac Trans Am good scoops facing backwards? The speeds of most boats isn't fast enough to matter anyway, if you exhaust the engine compartment enough, it will draw on fresh air itself.
 
fibersport said:
Honestly the vent direction doesn't really matter, it's all about low vs high pressure. Remember the Pontiac Trans Am good scoops facing backwards? The speeds of most boats isn't fast enough to matter anyway, if you exhaust the engine compartment enough, it will draw on fresh air itself.
Click to expand...

Thanks for feedback. I saw a thread about vent direction on another site, and found interesting post by a guy who said all of his vents face aft, and credits something called "The Bernoulli Effect" as to why they should face aft.
 
I am sure there is a formula somewhere i would pull from up high in the bilge with one blower and down low in the bilge with the other. That way your removing the gasses evenly. The fresh air coming in does two things it keeps the area cool and provides combustion air for the engines. As long as the intakes are unobstructed there should be plenty of air coming in. Maybe even open up the intake holes larger than the exhaust.
 
I would not waste one dime on an “in- line” or “turbo” blower motor! They are noisy, and they live a rather short life.
Instead, go with a continuous duty squirrel cage unit!


I have a good friend who is in the boat salvage and parts business. He will not sell one of the little plastic in line or turbo blower units because they will be returned in short order!


I agree...... you want the blowers arranged so that they pull negative pressure within the Engine bay!



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