Who runs their engine compartment blower constantly while on the water??

[a70eliminator]

Re: Who runs their engine compartment blower constantly while on the water??

Sounds like an excellent experiment for Mythbusters.

 

[cmcpherson]

Re: Who runs their engine compartment blower constantly while on the water??

I only posted how I do it to answer the original post so don't assume I meant not to run the blower whenever you want. My post was only meant to bring attention to the fact of when most explosions happen and that air is exchanged in the bilge when the engine is running.

I'll add this...If you run blowers full time be aware that melted blowers (there goes your spark protection) happens WAY more often than explosions from gas fumes. Have any of you examined your blower lately? It's another live electical circuit that can short, start fires or ignite gas fumes. Never heard of "valve covers popping off" but they wouldn't make fumes for explosions.The only thing they could do is let oil go in places that might ignite it. A blower would fan the flames so it would be wiser to shut the blower off if a fire started.

Even the smallest fuel leak while running will quickly overcome the blower and engine cfm anyway. Put about 10 drops of raw fuel in an open container in your bilge (don't start the engine on this one please) and see how long it takes for the blower to evacuate the fumes. I tried it 30+ yrs ago in a bottle cap and strong fumes stayed until the gas evaporated.

bp

Ok, so why bother to run it at all?

 

[a70eliminator]

Re: Who runs their engine compartment blower constantly while on the water??

The blower's pupose is diluting the fuel vapors to a non volitile ratio of fuel to air, what that ratio is I haven't got a clue.

 

[cmcpherson]

Re: Who runs their engine compartment blower constantly while on the water??

Ok, but the other guy said that even a small leak will overcome the blower so isn't it irrelevant?

 

[tommays]

Re: Who runs their engine compartment blower constantly while on the water??

Gasoline has an LEL of 1.4%, a UEL of 7.6% and a flash point of -45 degrees F. In a confined area, above -45 degrees F, gasoline fumes that exceeded .14% of the atmosphere would be considered a hazardous situation and all personnel should be immediately removed. If the gasoline fumes are between 1.4% (14,000 ppm) and 7.6% (76,000 ppm) then any sort of ignition source, i.e. spark of some kind, could cause the atmosphere to ignite or explode.

 

[1976SRV190]

Re: Who runs their engine compartment blower constantly while on the water??

My Sea Ray says it needs to only be run before starting, and when going slow, like under 10mph. I forget to turn mine off sometimes and realize it after about an hour....so I shut it down if I am above say 10mph, so I run it before I start the boat, and while in a no wake area, and when I beach the boat of launch or dock it. Mine has pretty good ventilation and no fuel leaks so I am probably fine only using it durring start up.

 

[cmcpherson]

Re: Who runs their engine compartment blower constantly while on the water??

Gasoline has an LEL of 1.4%, a UEL of 7.6% and a flash point of -45 degrees F. In a confined area, above -45 degrees F, gasoline fumes that exceeded .14% of the atmosphere would be considered a hazardous situation and all personnel should be immediately removed. If the gasoline fumes are between 1.4% (14,000 ppm) and 7.6% (76,000 ppm) then any sort of ignition source, i.e. spark of some kind, could cause the atmosphere to ignite or explode.

Ok, now we are going somewhere! My guess is that the blower will overcome those levels, otherwise why would there be any recommendation on the length of time the blower should be run before starting the enging. Which gets back to my original point, there is a reason to have the blower and a small fuel leak will not overcome the ability of the blower to vacate the fumes, especially underway.

 

[salty87]

Re: Who runs their engine compartment blower constantly while on the water??

Ok, now we are going somewhere! My guess is that the blower will overcome those levels, otherwise why would there be any recommendation on the length of time the blower should be run before starting the enging. Which gets back to my original point, there is a reason to have the blower and a small fuel leak will not overcome the ability of the blower to vacate the fumes, especially underway.

hmm, i don't know what to make of those numbers. i couldn't say blower would or would not handle that spill.

i'd say manufacturers toss out as many precautions and warning stickers as they can in a race to try to reduce their liabilities.

what if your blower burns out, as mentioned before, when you're out on the water? it was running for 7 hours (doing little, if anything, while the engine was running) and now you need to start the engine to get back to the ramp. sure, very doubtful it would happen but if the blower isn't doing anything productive while the engine is on, what's the point?...wear it out? why not leave your fenders out all the time because you never know when you'll need them too?

 

[cmcpherson]

Re: Who runs their engine compartment blower constantly while on the water??

hmm, i don't know what to make of those numbers. i couldn't say blower would or would not handle that spill.

i'd say manufacturers toss out as many precautions and warning stickers as they can in a race to try to reduce their liabilities.

what if your blower burns out, as mentioned before, when you're out on the water? it was running for 7 hours (doing little, if anything, while the engine was running) and now you need to start the engine to get back to the ramp. sure, very doubtful it would happen but if the blower isn't doing anything productive while the engine is on, what's the point?...wear it out? why not leave your fenders out all the time because you never know when you'll need them too?

Well I know in my case, there are 2 reasons I leave mine running, first I forget to turn it off. And second, if I do remember to turn it off, I forget to turn it on when I should. So, I have decided to leave it on when I am running so I will not be sorry that I forgot to turn it back on.

 

[a70eliminator]

Re: Who runs their engine compartment blower constantly while on the water??

I just read in my manual the gasoline will explode violently when ratio of 5 parts fuel to 100 parts air by volume is reached. Running the blower (if it's set up right) will keep the space diluted with enough fresh air. The blower is capable of xxx cubic feet per minute (if it's set up right) which will exchange 100% of the air in the space, the 5 to 1 ratio will never happen unless the air is still.

 

[Zero Balance]

Re: Who runs their engine compartment blower constantly while on the water??

For the most part engine comparments do not have the passsive air flow they should

You will see seme more costly bost with a grill across the transome allowing lots of natural air flow

Most boats I see and the one I own have grills at the stern portion of the gunnels. These grills are actually an integral part of the ventilation system mounted in such a manner to collect air and move it through a cowling to introduce fresh air into the engine compartment. A very low speed or breeze will play a large role in this circulation. For this reason, I don't run a blower while underway unless I forget to turn it off for some reason.

This ventilation system usually will move far more air than a typical blower unit. The Blower unit is for moving air as needed when the boat is not moving or at rest IMO...

 

[DMRH]

Re: Who runs their engine compartment blower constantly while on the water??

Reads like a 50/50 subject.

50% safety concious
50% complaciant

Unless you have custom wired your boat. Its little wonder that a blower isn't hard wired to the IGN position as standard fitment.

REgards

 

[cmcpherson]

Re: Who runs their engine compartment blower constantly while on the water??

damned if you do, damned if you don't...

 

[marine4003]

Re: Who runs their engine compartment blower constantly while on the water??

In addition to purging the engine compartment of fumes,i run mine to keep the engines cooler,i run 2 Jabsco 4" with a combined total of 500 cfm, and with 2 - 750hp motors running...every little bit helps

 

[Willyclay]

Re: Who runs their engine compartment blower constantly while on the water??

Machines wear out or break and human beings make mistakes. Be safe!

 

[bamadave]

Re: Who runs their engine compartment blower constantly while on the water??

I'm surprised at the responses. 36 post and only 1 mentioned he opens his engine compartment before he starts the engine. The first time out EVERYTIME I open the cover, check all oil levels , look over the engine for anything amiss, check bilge for anything unusual, also while doing all this the compartment is breathing, then after closing up, the blower goes on as long as the engine is at fast idle or below, as per recommendation.

If you had witnessed a boat exploding when starting, I seriously doubt you would ever forget to turn the blower on and every other precaution you can take before starting.

 

[BillP]

Re: Who runs their engine compartment blower constantly while on the water??

Geez, this shouldn't be so difficult. Run blowers full time or part time...do whatever makes you feel warm and fuzzy. The "right" way is how you want to do it. The wrong way is not following USCG recommendations...which is part time.

When to run them is most important after refueling because the fumes settle. 105 cfm is the smallest and 250 cfm about the largest 12v blowers out there. They will purge fumes from refueling and if you want to myth bust do what I posted earlier. Place a soda cap full of gas in your engine compartment by the carb or where gas leaks would happen, shut the hood and turn the blower on. Come back in 15 minutes and use your nose. The gas fumes will still be very strong (there are always exceptions). The "rule" is don't start the engine if ANY gas fumes are smelled. You can also figure an additional 400-800cfm of purging would have happened if the engine was running fast.

Blowers can suck some serious batt juice and the suggestion of wiring directly needs to be taken with caution. 105cfm blowers draw 4.4 amps and 250cfm blowers draw 12 amps. Be ready for it if adding blowers to keep up with a spurting gas leak while running. If 24 amps is wired directly through most marine ignition switches it will cook the switch. Starters take 20A and coupled with blowers could be an easy way to get stranded or melt stuff. Production boats commonly have 15A or 25A continuous switches. Some have only 5A continuous but 35A switches are out there too.

I'm done.

 

[LouisJamesNYC]

Re: Who runs their engine compartment blower constantly while on the water??

The first thing I do when I board is open up the doghouse partially if not fully to air out the engine compartment. I wait a few minutes, start the blower, then hit the ignition. Then I do a quick visual inspection of the running engine (most of the time, I'll admit often I forget) before replacing the doghouse.

Yeah, it's kinda time consuming and a bit a drag to passengers (read: noise), but I feel I am being extra safe this way.

Cheers,
Lou

 

[Boatist]

Re: Who runs their engine compartment blower constantly while on the water??

All the engine checks and the boat ramp are not needed. Check you engine and fuel hoses at home the day before your trip. In the spring you check all the hoses make sure they are not cracked and are double clamped class A hoses.

Make sure your blower is set up correctly so it sucks air from low in the bilge below the engine. Before starting turn the blower on and go back and use the best fuel spill detector there is. Use you nose to smell the output air of the blower. Nose is by far the best detector.

By the way most boats that blow up after fueling do not do so at the fuel dock. They blow up after leaving and 100 yards out. I fuel up at a gas station 99 percent of the time and drive to the launch site or home. This gives the cowls a lot of time to exchange the air in the bilge.

Also one should know how many gallons they need when fueling. If you put 30 gallons in a 34 gallon tank that was half full then stay away from me.