Bilge Safety

[Dave Neptune]

Adninistrator, I have reviewed many posts over the years and one thing keeps coming up that concerns me as far as safety is concerned. I have witnessed two gas related explosions on boats however both were on a power boat. In both instances neither was using the "Blower" to keep the engine-box/bilge vented. I have seen many posts regarding Co and smoke detectors in which they stated that they turned the Blower back on because of fumes. This scares the krap out of me.

My personal starting drill is to remove the key from the raw water valve while opening it which gives me a good opportunity to sniff the air. Then I start the blower prime the carb, close the choke and then stick my nose in the blower exhaust vent on the transom. If I smell no fuel I start the engine.

Whenever my engine is running SO IS THE BLOWER for safety and keeping a better flow of cool fresh air around the engine.

I would like to see a pole on how many actually cruise with the BLOWER off or on. I am also interested in seeing the comments that will follow.

Thanx, Dave Neptune

[Bob.Griffin]

I share your concerns, one cannot be too careful with a gas engine on board. I have a gas fume detector located about 9 inches from the carb, fuel pump and Racor filter, and I actually test it periodically with a gas-soaked kleenex. I also leave the engine compartment door open (it slides) providing about a 6 inch by 12 inch gap, if I smell gas in the cabin I then check the engine compartment. While the engine is running I figure I have a good flow of air through the engine compartment door and out through 2 dorades on the stern. However, I am very close to wiring the bilge blower fan directly to the ignition so that it runs at all times when the engine is running, the only problem being that I need a parallel switched line to the blower so I can turn on before switching the ignition on, in the event of needing to clear any fumes during servicing for example.

Bob, s/v Dovetale

[smosher]

I sniff for gas when I turn on the gas and the water. Then I turn on the blower. I will usually run the blower for several minutes before and after I start the engine. I had a small gas leak in the cover to the fram gas filter and its very noticeable when I went to turn on the gas.

I also have on my P30 two dorades for fresh air into the engine compartment.

Steve

[Mark S]

Whenever my engine is running SO IS THE BLOWER for safety and keeping a better flow of cool fresh air around the engine.

Probably a good idea. Trouble is, most blowers were not designed to run for long and continuous periods of time. I have vents that bring in and take out air; I have the companionway hatch open; and I have the engine compartment doors open. This gives ample fresh air to the engine compartment. I run the blower before starting every time and I don't start without the "sniff test", but I do not run the blower all the time the engine is on. I should probably revisit this issue in my procedures and look for a blower that is capable of indefinite running.

Mark

[Administrator]

actually cruise with the BLOWER off or on

Dave:

Do you mean while the engine is running, when it's not, or both?

Bill

[Dave Neptune]

Blower

Bill, I actually mean on whenever the engine is running regardless of the dorade vents hatches etc. I have many friends whose boats I am leary of sailing with diesels as they just hit the starter and go. When I ask about the blower that they are equiped with they say it's a diesel and doesn't need to be vented~~~~BS.
I use a continuous duty type and it has been in service for at least 10~12 years now. I even let it run for a few minutes when I shut the motor down.

Thanx David

[Kurt]

I have to climb into my lazarette, which is part of the engine compartment, to turn on the water and gas so I take this opportunity to take a sniff. I have had a gas leak from the carb before and the smell is undeniably obvious. I then turn on the blower for a couple of minutes and run it the entire time the engine is running. My last blower only lasted for 2 years, but hey - they are cheap!

[rigspelt]

Our blower is very loud, obnoxious and an amperage hog. May need to rethink procedures.

[ndutton]

My practice is to run the blower about five minutes prior to starting and continuously while the engine is running. In addition, I have the Xintex MB-1 Gas Fume Detector that emits a shrill alarm and automatically turns on the blower if combustible fumes are detected. The system shuts down the blower when the fumes are evacuated. I keep this system on at all times even when I'm not at the boat. It keeps an eye (nose??) on things when I can't. It's available at West and I recommend it highly.

Neil
77 Catalina 30

[keelcooler]

As Dave said,incorporate sticking your face in the engine bay as part of your start up procedure (opening raw water cock). Any explosive fumes and you will know.
I shut the blower off when the engine starts. Run your blower for an extended time and fell how hot that sucker gets.
Mark is right, our under $100. blowers are not designed to run continuous.Our econo blowers are for intermittent cycles only.
Just like all electrical stuff in the motor bay the motors per Coast Guard must be shielded to prevent a spark source.
Overheat the blower motor and you may degrade the shielding. How many blowers have you herd squealing? They are worn out but still running. Our econo blower manufactures recommend replacement after eight or nine hundred hours.
When running you should have a natural venting duct,cowl and feel air flow at the motor duct end.
Most gas fume explosions occur right after refueling. This is the time to open the fuel tank hatch and religiously check fill,vent and tank surfaces for a wet spot or fumes.
We must not overlook electrical and raw fuel fires in are motor box.This risk is by far the most common.
All engine fires I have been involved in could not be extinguished by owner or crew.
All engine fires I have been involved in with an automatic haylon type extinguisher were put out before the operator even knew of a problem.
They work and that's why your insurer will offer a discount upon install.

[Mark S]

I use a continuous duty type and it has been in service for at least 10~12 years now.

Dave, what do you have for a blower? I want one.

Mark

[ndutton]

All good points and I want a continuous duty blower too.

It seems to me that with the engine running, fuel pump pumping and fuel flowing, the possibility of a fuel leak is enhanced and at a time when I’m on deck rather than in a position to sniff the bilge. I’m still more comfortable with powered over natural ventilation and if my blower starts complaining I’ll replace it like any other worn out component.

It also seems to me that the blower and Halon extinguishing system serve different purposes. The blower is intended to remove dangerous fumes before something catastrophic happens while the Halon system minimizes the damage after the catastrophe. One system isn’t preferable to the other, they both perform essential functions.

Neil
77 Catalina 30

[keelcooler]

Yes Neil, a haylon unit is the bilge safety equipment item of last resort.
Take a look at the fried fuel pump recently pictured.No way is a blower going to reduce a fire hazard if that hole was gushing raw fuel.

Continuous duty blowers are available for just under $300. You mostly see this model blower serving a generator box. A good blower venting your box all the time is good. A hot cheep blower running all the time is bad.

Most of our boats have 3" blower systems.All heavy duty blowers are 4" and will require 12 amp draw. If you upgrade make sure your wiring can handle and install 15 amp fusing.

[tenders]

I run my blower all the time and am not particularly concerned about wearing it out. I keep the blower running to remove any fuel fumes, but also to cool the engine compartment and ventilate it in case any exhaust fumes leak out. The last blower lasted, I think, 32 years and it doesn't look to me like the new blower will have any problem lasting a good long time either.

The boat originally had a blower switch at the DC panel and another switch in series in the cockpit. Both had to be turned on for the blower to work. This was slightly inconvenient, so as of last year my blower is wired (and fused) into the "accessory" position on my 4-position keyed ignition switch (Off/Acc/Ign/Start).

My procedure is:
* Remove engine cover, verify raw water intake is open, and sniff for fumes
* Turn blower on via key (I do this after sniffing)
* Stow gear on board, feel for airflow coming out of blower vent, sniff airflow coming out of blower vent (this usually takes 3-5 minutes)
* Start engine, look overboard to confirm coolant flow out the exhaust
* Keep blower on for a few minutes after engine is shut down
* Turn blower back on for a minute or so before restarting engine

[Dave Neptune]

Blower??

Mark, I have no idea who manufactured my blower. I went through 2 blowers in the first ten years of opperating Volador. When that last one expired I went to a marine supply while in Santa Barbara (it failed at Santa Cruz Isl.) aand bought the best one they had to fit my ducting. That was about 12~15 years ago. When I am at the boat again this weekend I will give a look under the lazzerate to see if the name is visable. I do know that it is a "squirrel cage" type and it really moves a lot of air.

For those who don't like the noise mount them on rubber isolators. I remounted mine after returning and it made a huge difference quieting the noise as well as dampening the vibration and associated noises.

Dave Neptune