Running bilge blowers?

BryanOnTheBay said:
That is what I have read as well. I don't run the blower while refueling as there is a risk of sucking in the gas vapors, but it goes on when done and I always check for vapors. I don't think the blowers are necessary at speed, but I generally forget to turn the off when I head to plane. No harm done. They are meant to be used, and have a long service life. I certainly don't want to find out personally what happens when a boat explodes.

Bryan
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I agree, I don't run my bilge blowers whilst refuelling either for the same reason. If there is a leak from the refuelling hose, a bilge blower isn't going to take care of the fumes from a bilge filling with fuel and an explosion very possible

I also turn off all my electrics so there can be no chance of a spark in the bilge if an electrical circuit in the bilge kicks in. This is where an inspection of the bilge after refuelling important so that any leaks after refuelling are detected before setting off again....and is far more reliable than relying on your bilge blowers. As mentioned before, I am guilty on not checking my bilge after refuelling though.
 
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My blowers are on 100% of the time, unless boat is off. When fueling, I also click all batteries off. Replacing blower, if need be, is easy. Peace of mind and family safety is priceless.


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Craigalan said:
My blowers are on 100% of the time, unless boat is off. When fueling, I also click all batteries off. Replacing blower, if need be, is easy. Peace of mind and family safety is priceless.


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How is the blower running when fueling if the battery is off?
 
When fueling...the batteries are off. Thus...the boat is turned off. Thus...no blowers when gassing up.


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Craigalan said:
My blowers are on 100% of the time, unless boat is off. When fueling, I also click all batteries off. Replacing blower, if need be, is easy. Peace of mind and family safety is priceless.


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I personally would not turn off the batteries while fueling. The simple act of turning them back on could introduce that spark we all want to avoid. As a general rule electrical circuits are stable when energized provided there isn't a fault. Except for a very loose connection, sparking only happens during the brief moment when current is applied.
 
Yep, 4th of July we're taking a huge box of fireworks, anchoring out and fire them from the swim platform........
 
Every boating course I've ever taken all say to SHUT OFF BLOWER and close all hatches and turn off all electrical items before beginning to fuel up. Upon completion of fueling, OPEN doors and hatches, check bilge for fuel vapors and THEN turn on blowers for a minimum of 5 minutes prior to starting engines.
On my boat, the fuel deck fills are located about two feet aft of the bilge vents and running the blowers while fueling would most certainly suck fuel vapors into the bilge.
 
Great point about NOT turning batteries off. I have removed that step from my routine because of it. Always good stuff everytime I visit CSR. Now...back to my shrimp.
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I've often wondered about the effectiveness of the vents at speed. My boat has two vent, one port one starboard, above the swim deck. Each vent has a flexible hose that is routed below the single engine. Once the port vent has a vent motor. I've always assumed the forward motion of the boat on plane forces air into the vents the same way air blows into a station wagon with the rear window open. If this is the case, with the blower off air is being forced in through both vent with no true outlet. So running the blower should draw air out even on plane, assuming it can overcome the pressure of the inward traveling air.
I am rarely on plane and the blower is not loud enough to be a nuisance, so I run it pretty much all the time anyway, but having definitive explanations of how the system works would be nice.
 
tdgard said:
I personally would not turn off the batteries while fueling. The simple act of turning them back on could introduce that spark we all want to avoid. As a general rule electrical circuits are stable when energized provided there isn't a fault. Except for a very loose connection, sparking only happens during the brief moment when current is applied.
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If an electrical circuit has no faults there is no risk. The risk is when there is a fault and there are fuel vapours present in the bilge. Assuming you leave the batteries on, and the aircon pump or black water holding tank vaccum generator has just developed a fault and kicks in? What if the running bilge blowers have a short?

Switching the batteries off, refueling and then checking the bilge before energizing the electrical system would overcome or mitigate this risk, even if there is a subsequernt electrical fault. The only remaining issue I see with this process is that I understand the bilge pumps remain energized even if the electrical system is switched off at the panel - so a fualty bilge pump could still cause an explosion.

I've personally had one of the plug leads arcing out against the exhaust manifold during a trip, but having checked the bilge for fuel vapours before embarking on the trip mitigated the risk of explosion, with the only risk being that a fuel leak developed during the trip. Installing a gas vapour detector would further protect against such risks.
 
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juggernaut1 said:
If an electrical circuit has no faults there is no risk. The risk is when there is a fault and there are fuel vapours present in the bilge. Assuming you leave the batteries on, and the aircon pump or black water holding tank vaccum generator has just developed a fault and kicks in? What if the running bilge blowers have a short?
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I do turn everything off while fueling and only run the blowers after that is done. If one of those systems had a fault and you had vapors present, of course there would be a problem. My position on this is that by turning off the batteries you have deactivated the one piece of equipment designed to remove fuel vapors on the boat until you throw a switch that supplies voltage to everything.

And yes, I fart at open flames, run with scissors, drive fast and take chances.
 
Craigalan said:
Great point about NOT turning batteries off. I have removed that step from my routine because of it. Always good stuff everytime I visit CSR. Now...back to my shrimp.
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Yum!
 
tdgard said:
My position on this is that by turning off the batteries you have deactivated the one piece of equipment designed to remove fuel vapors on the boat until you throw a switch that supplies voltage
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But running the blowers has the potential to draw the fuel vapours in which are present outside of the boat courtesy of fuel tank breathers as the tanks are filling. Whilst the blowers evacuate the air from the bilge, the replacement air is drawn through the bilge vents laden with fuel vapours. So you've potentially exacerbated the problem by running the blowers whilst refuelling and filled the bilge with air containing the vapours.
 
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juggernaut1 said:
But running the blowers has the potential to draw the fuel vapours in which are present outside of the boat courtesy of fuel tank breathers as the tanks are filling. Whilst the blowers evacuate the air from the bilge, the replacement air is drawn through the bilge vents laden with fuel vapours. So you've potentially exacerbated the problem by running the blowers whilst refuelling and filled the bilge with air containing the vapours.
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You seem to be misreading my posts. I do not and have never run the blowers while fueling.
 
My problem with running the blowers while fueling is it draws in my cigar smoke to the engine room.
 
tdgard said:
You seem to be misreading my posts. I do not and have never run the blowers while fueling.
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Yes you did say that, then your following statement I quoted it above made it unclear...to me at least....but all clear now.
 
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I have to say... reading this thread made me put my blowers on the whole time I was underway this past weekend... boy was it annoying
 
So....when we had a gasoline engine boat we were very careful about running the bilge blowers prior to starting the engine, immediately after fueling and occasionally when at idle speed for a long time. Now that we have diesels we were told that it's not really necessary. After reading this thread it still appears that it may not be necessary but I'm still curious. Diesel owners - what's the consensus? We've never used the bilge blowers on our 450. The switch for them is in the cabin on the DC panel - not exactly in the handiest place.

Sandy
 
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