What is your version of Cruising Speed

Has anyone ever measured the temperature of the engine room at cruise with and without the blower on?
 
We cruise (slow) at 1700 rpm, 6.7kn, 7.7mph; and on plane at 3400-3800 rpm, 21-24kn depending on load and whether the bottom is weedy/scummy or not. If we are on slow cruise and have a following wind, I make sure the blower is running, as I figure the unassisted air flow through the vents won't be much at all. Otherwise, I turn the blower off once we reach our slow cruise speed or get on plane, IF I REMEMBER TO!
 
comsnark said:
For me, it takes about 10 minutes from the dock to the end of the "no-wake" zone.

I usually turn off the blowers about 5 minutes away from the dock. Yes, I frequently forget.

I STRONGLY believe in opening the engine hatch for a quick look before taking the boat for a ride. One time, I found that one of the belts was nearly off the power steering pulley.Sticking a nose down there will do a lot more to detect fuel leaks than sitting at the helm.

I also believe in running the blower when at the fuel dock. Not hard to get a few drops where you don't want it.

I do NOT personally believe in running the blower for giggles when running at idle. I can't believe it would do that much good if something bad happens when running. Call me a contrarian.
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I believe it is bad practice to run the blowers or anything electric while at the fuel dock. In fact, I believe that the battery switch should be fully off when fueling. Our rule is, all passengers off, I stay on to fuel, battery off, fire extinguisher handy, contact the fuel neck with the chain tether of the gas cap to ground and then fill.

After its full, cap closed, engine hatch open to sniff, battery switch on if clear, then blower for no less than 4 mins with extinguisher still at the ready as it turns over.

I would rather not be a french fry. I don't look good in ketchup.
 
I am confused about running vs not running blowers while fueling.

If it is unsafe to run the blower because of the potential to ignite fumes while fueling. . .then presumably it is unsafe the run the blower because you could ignite fumes that built up while the boat was sitting for a week.

What am I missing?
 
On weekends usually 2000 rpm or 4.5 mph. The lake has narrow channels and lots of can boats so we have to watch our wake. If the lake is clear...3500 rmp 25-27 mph/ As far as the blower, I turn it off when my wife reminds me.
 
comsnark said:
I am confused about running vs not running blowers while fueling.

If it is unsafe to run the blower because of the potential to ignite fumes while fueling. . .then presumably it is unsafe the run the blower because you could ignite fumes that built up while the boat was sitting for a week.

What am I missing?
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Your actually right on...I'm no chemist, but fuel vapors need a certain % to ignite. (from my fireman days) You can get to that % either way,maybe turning the blowers on gets you there too.... Frankly if your boat is well maintained you should not have any vapors in the engine room period. Your point is correct IMHO.
 
comsnark said:
I am confused about running vs not running blowers while fueling.

If it is unsafe to run the blower because of the potential to ignite fumes while fueling. . .then presumably it is unsafe the run the blower because you could ignite fumes that built up while the boat was sitting for a week.

What am I missing?
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I've been scratching my head on that one too after a few posted that in this thread. I've got the blower running as I come off plane going into the marina and including while I'm refueling; I don't see how enough fumes could build up down there in the first place if I've had the blower running.

BTW, I open the bilge cover before I head out to the lake and have never smelled fumes even after the boat has been sitting for months.... if I ever did, I'd figure out why and fix it before taking it out in the first place.
 
if you're going to turn your blowers on for 4 minutes after fueling, why wouldnt you go KABOOM right then and there? at least if they're running as you fuel, any vapors will be dissipated as they enter the ER as opposed to being allowed to build up during the 10-60 minutes it takes to fuel up.

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comsnark said:
I am confused about running vs not running blowers while fueling.

If it is unsafe to run the blower because of the potential to ignite fumes while fueling. . .then presumably it is unsafe the run the blower because you could ignite fumes that built up while the boat was sitting for a week.

What am I missing?
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Here's the reason why...

1. When fueling vapors are outside the boat near the nozzle, etc.

2. You turn on the blower and what you end up doing is sucking the fumes down into the bilge via the fresh air vents (used to supply fresh air to the engines while underway). With the hatch closed, the bilge becomes a sealed environment. Turning on the blowers creates a vacuum and thus fumes comes in through those vents.

Doug
 
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Also, the blowers can be a source of ignition. You should check for pooled gas after fueling and BEFORE turning on the blowers (I do the "smell" check).
 
I agree but I guess I still am not totally grasping it. What I meant to say when I posted was that I have the blower on as I come in and as I am fueling - I am not docking and then turning on the blower as I am fueling or right after I am fueling. My thought is that if I have it on before even getting there and keeping it on, it will never give any fumes the chance to settle in the engine bay. Even fumes that may be possibe from the fueling hose (if sucked in) simply continue course right through and out the other side before enough have a chance to accumulate. Right(?)

On the other hand, I do see the problem with docking, fueling, and THEN turning on the blower during the refueling (or immediately thereafter). That's why I have circulation already occurring beforehand.
 
GJarrett said:
I agree but I guess I still am not totally grasping it. What I meant to say when I posted was that I have the blower on as I come in and as I am fueling - I am not docking and then turning on the blower as I am fueling or right after I am fueling. My thought is that if I have it on before even getting there and keeping it on, it will never give any fumes the chance to settle in the engine bay. Even fumes that may be possibe from the fueling hose (if sucked in) simply continue course right through and out the other side before enough have a chance to accumulate. Right(?)

On the other hand, I do see the problem with docking, fueling, and THEN turning on the blower during the refueling (or immediately thereafter). That's why I have circulation already occurring beforehand.
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Im not sure if we are correct, but I am thinking the same thing...I leave it on during fueling as well, and it is on before I get anywhere near the dock to fuel (mostly just because I havent even turned it off yet that day:huh:)

I owuld think this would help regardless? Hmmm...wonder if there is a "correct" answer.
 
I keep my blowers on prior to starting the engines (15 minutes)and throughout the entire cruise. Even if I am anchored I keep her on (if the gen set is running). She is then turned off once I get back into my slip. I also check the engine room for all sorts of things prior to departure. Tends to be hard at times when kids, dogs and cooler is in the aft area where my engine room hatch is located.
 
Well. . .not sure I am buying it.

Clearly, the MOST conservative approach would be to sniff check the bilge at the start of the day to ENSURE that your entire bilge isn't filled with fumes BEFORE turning on the blower. I strongly doubt the blower is rated for hazardous area (i.e. is a non-sparking motor). As a serious question: Does the manual recommend that?

At the fuel dock, I can't buy the "blower will suck in gas fumes" argument. Ok. .. the blower will suck in gas fumes. Then what happens? The blower blows them right back out of the boat from the point they are most likely to collect! How much gas fumes do you think can be sucked in during fueling? Keep in mind where you are relative to the fuel hose during this operation. If the ambient area was filling with fumes. . .you would know it.

During filling. . . if I dump a small amount of gas into the bilge, I want the blower already running. If I dump ALOT of fuel in the bilge. . . then I have a problem. My first indication would not be a "boom", it would be the bilge pump kicking on and spewing gasoline into the water. Afterall. . . it's not like the bilge can hold 50 gallons of fuel. At that point, I would stop the blower and open the hatch to vent it.

And remember. . the bilge pumps are hardwired. Turning off your battery switches won't prevent your non-hazardous-rated bilge pumps from kicking on if you pour 50 gallons into the bilge.
 
I think we all need to switch over to diesels. Diesel fuel is non-explosive at atmospheric pressure and normal temps.
 
comsnark said:
Well. . .not sure I am buying it.

Clearly, the MOST conservative approach would be to sniff check the bilge at the start of the day to ENSURE that your entire bilge isn't filled with fumes BEFORE turning on the blower. I strongly doubt the blower is rated for hazardous area (i.e. is a non-sparking motor). As a serious question: Does the manual recommend that?

At the fuel dock, I can't buy the "blower will suck in gas fumes" argument. Ok. .. the blower will suck in gas fumes. Then what happens? The blower blows them right back out of the boat from the point they are most likely to collect! How much gas fumes do you think can be sucked in during fueling? Keep in mind where you are relative to the fuel hose during this operation. If the ambient area was filling with fumes. . .you would know it.

During filling. . . if I dump a small amount of gas into the bilge, I want the blower already running. If I dump ALOT of fuel in the bilge. . . then I have a problem. My first indication would not be a "boom", it would be the bilge pump kicking on and spewing gasoline into the water. Afterall. . . it's not like the bilge can hold 50 gallons of fuel. At that point, I would stop the blower and open the hatch to vent it.

And remember. . the bilge pumps are hardwired. Turning off your battery switches won't prevent your non-hazardous-rated bilge pumps from kicking on if you pour 50 gallons into the bilge.
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If someone chooses to have the blowers on while fueling and then turns off the blowers when fueling is done, there are still residual fumes in the bilge. I do agree with you that there is a cyclic process going on. Yes, you and others may know to run the blower 4 minutes after fueling, but what if someone just thought run it for only the fueling period? Now when you go to start the engine, there is a greater chance of an explosion.

Doug
 
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HudsonHauler said:
... Our rule is, all passengers off, I stay on to fuel, battery off, fire extinguisher handy, contact the fuel neck with the chain tether of the gas cap to ground and then fill.

After its full, cap closed, engine hatch open to sniff, battery switch on if clear, then blower for no less than 4 mins with extinguisher still at the ready as it turns over.
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I agree with getting everyone off the boat and not running anything electrical while fueling, but... Do you go through this practice when fueling your car?:huh:
 
Some very good points here. I agree with Hampton as I also do the sniff check under the hatch before first starting the boat when I arrive, or after being fueled. Actually, my wife has a better nose than I do so she usually does this. As far as the blower is concerned, I run it all the time, there is pobably no good reason for this except it makes me feel better as I know there is always fresh air in the engine room. We also do the sniff check in the cabin before starting after fueling, I don't think there is such a thing as being too cautious when it come to starting up your boat after its been sitting a few weeks or after fueling.
 
How many boats actually blow up every year due to fueling practices that didnt involve a leak of some kind? I googled the crap out of this subject, and could only find explosions from leaking pipes etc...
 
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