Bilge blowers

R

Roy

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114
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I have gasoline powered project boat into which I intend to install 2 bilge blowers. Should I install them so they are both exhausting the air or so that one is blowing fresh air in and the other is exhausting air?

Thanks.........Roy
 
+1 On above. They should always remove potential dangerous from the bilge, not bring in air
 
Overheard from an adjoining motel room "Suck...blow is just an expression!!" Same is true with bilge blowers.
 
If you think about it it is a simple plus/minus equation... if the blower is sucking air out of the engine room there must be a way for fresh air to get in... by having the blower vent to the outside you are creating a negative pressure in the ER which can only be countered by air being sucked in from any small opening or vent... I suppose in a really bad design you could be sucking the air out with the blower and then have an intake vent close enough to the outgoing air as to have that dirty air sucked back into the ER causing a dangerous situation?
 
Bear in mind that the bilge blower is supposed to be ducted to a low point in the bilge so it will suck out GAS VAPORS which are heavier than air. If it blew in it would just stir them up. If it sucked from a high point without the duct it would be pretty much useless.
 
My boat is diesel. The blowers blow air into engine compartment rather than suck air out. I contacted manufacturer and they stated that this was as designed based on recommndation from engine manufacturer (volvo) at the time (2000). They have since changed this. They indicated it would be fine to reverse the layout. However, the end of the duct is near the top of the engine compartment.
 
I had a Factory made 24' and a 27' by a different Mfg.
Both had the Bilge blower way up in the bow, and it ducted the air back through the Bilges and out the engine room ducts.
We had this discussion two or three years ago.
I was resoundingly crushed!
But...I've never agreed with sucking fuel laden air past an Electric Motor.
 
but on the other hand why would you want to blow fuel laden air in to your cabin.
 
But in the case of fuel laden air, it is sucking it past an ignition protected device.
 
quote:
Originally posted by PascalG

Blowers always suck out of the ER

Click to expand...


This is very important. Recommend anyone looking for an answer to the original question read Pascal's response a couple hundred times.

Do NOT, DON'T, for ANY reason, pipe forced air INTO a gas engineroom. Terrible, horrible, no good, very bad idea.
 
In the event of a fire blowing air toward a that fire would not be good.
 
quote:
Originally posted by getakey

My boat is diesel. The blowers blow air into engine compartment rather than suck air out. I contacted manufacturer and they stated that this was as designed based on recommndation from engine manufacturer (volvo) at the time (2000). They have since changed this. They indicated it would be fine to reverse the layout. However, the end of the duct is near the top of the engine compartment.

Click to expand...


I think the difference is in the purpose of the blower. In your case (and mine), they are there to cool the engine room, not to exhaust vapors. In that case, suck or blow makes no difference.
 
quote:
Originally posted by cmariner32

But in the case of fuel laden air, it is sucking it past an ignition protected device.

Click to expand...


The more expensive (better?) blowers use a centrifugal fan and do NOT blow air past the motor.
 
On a diesel the blowers are just there to cool the ER and also be suckers not blowers. Since fumes are not an issue they don't need ducting and can be near the ceiling where in theory the hotter air is. Although.. Obviously when you have a few tons of hot steel in there, it s hot everywhere!!

I always run them for a few hours, even overnight after a long run, to help control temp especially when battery chargers and other electronic gizmos are in the ER
 
I think some of you guys are living on Rumors.

If the Bilge is vented upwards and outwards, and not into the Cabin, the Fuel laden fumes will be the last to move.
The air pressure in the bilge by that time is near zero + Atmospheric so the flash point must be very high indeed to cause a problem.
As well as the Blower ducts are moving the Fuel laden Air away from the rest of the boat. And not through the boat toward the Bilge Blower.
Most Bilge Blowers are not in the Bilges for that very reason.
 
I'm not sure if that statement was another Thuddie, but the bilge blowers in all of my previous boats have been in the lower (bilge) area of the engine rooms. Perhaps Carver (last 3 boats) felt it necessary to endanger its customers by locating the blowers (suckers) in the bilge????
 
A properly designed machinery space on a diesel powered vessel should have a positive pressure of 1/2 p.s.i. when the machinery is running. This is accomplished with blowers that move air into the machinery space and blowers that move air out of the machinery space. Diesel engines (especially 2 strokes) use copious amounts of air when running. If your machinery is running in area that is negative in pressure, your machinery is working (expending fuel), unnecessarily, to pull air into the air box from a negative pressure environment. A properly set up machinery space, with the blowers in operation, should burp a small amount of air when ever the access door/hatch is opened. Production boats tend to have air flow restriction issues that manifest themselves as engine issues, especially in small boats that have been repowered with diesel engines.
 
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