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Engine Room and Venting

knuckle47

Advanced Contributor
Being deep inside the hull, I am replacing the 3" flex hose that runs from the vent boxes on each side of the hull to various places under the deck. Being nearly 30 years old, I question whether or not they are in the right places or not. Each side has 4 hoses and 2 of each go to the lowest part of the "V" in the engine compartment.

We added a power blower to one of the 8 lines when we got this thing but I am going to use two blowers ...is there any specific placement that should be followed?

Currently 4 of the hoses go in to the engine area and 4 are under the saloon floor. Thanks Al
 
I also added two, continuous duty Squirrel Cage blower motors for my twin engines.
The hoses coming from the blowers must go near the lower section of the engine bay..... that is where the heavier gasoline vapors will be.

Unless you have twin hoses per vent port/louver....., all others will be supplies and should be strategically placed.

Hope that helps.
 
Thanks for the reply. I assumed the lowest spot for vapors I am also concerned about the vent directions which I WOULD THINK, are scooping air in from the forward motion of the vessel. In looking at over 50 boats, there is no continuity from one to the other. Some face back some face forward, some have 1 forward and 1 backwards...this is all for the same side... The opposite side is also odd. I have two vent boxes on each side about12" long each and they have 2 hoses each, 4 per side
 
Al, I should have been more clear on that.

As you know, the direction of the vent louvers determine if these will remove air, or supply air, while under way!
One or two vent hoses would be arranged as such to provide suction to the lower-most areas...... and whether or not the blower motors are running (as long as the vessel is moving).
One or two would be arranged to provide air supply to the surounding areas.


I have a total of four vents!
Two aim fwd, and two aim aft!
However, via a change that I made to the design, my blower motors now have their own separate outlets that are independent of the four louvered vents.
They are continuous duty squirrel cage motors, and I choose to leave them running when ever the engines are running!
(all of this is over-kill, and not required)

So to me......, the second blower motor function (after initial purging of any gasoline vapors), is to bring in as much cooler air as possible while under way.
The cooler the air, the more the engines like it!

As long as your vents will move air correctly while under way, and to/from the correct locations, you should be OK.
 
Thanks Rick...That makes sense to me now. I did not think about the suction factor in moving the air but only of the pressure effect of it blowing in. I two feel better having the two blowers in place and they will likely be used accordingly.

I have always had interests in the obscure ...such as the air temp in the engine room while underway or in my attic at the house. To the point where I actually placed a remote temp sensor to keep a read on it...Whether normal or not ( I mean the temps ) I would have no idea. More useless information, maybe? Thankls Again
 
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I have always had interests in the obscure ...such as the air temp in the engine room while underway or in my attic at the house. To the point where I actually placed a remote temp sensor to keep a read on it...Whether normal or not ( I mean the temps ) I would have no idea. More useless information, maybe? Thankls Again
I have a similar system in my attic! Thermostat that kicks on a squirrel cage furnace fan..... wow does that sucker remove air from my attic!
It sucked out an old suit case and a few of my golf clubs onto the front yard! :D


Just make sure that your bilge blower motors Pull Air from the low point, and not supply air!

Steer clear of any so called "in-line" or "turbo" bilge blower motors.... they will not last, and they are noisy!
A friend of mine sells salvaged boat parts. He won't even sell a good used turbo or inline blower because it will come back in a week or so!
Spend a few extra dollars and buy the squirrel cage style! :)
 
Actually, in the attic we have roof ventilators. They suck literally and are also poor movers of air. I have always loved that huge gable end mounted exhaust fan that when you turn it on, the louvers open in the ceiling and if your windows are open the draperies flow inwards towards the room's center.

What had always freaked me out a bit was: I was in the medical examiners office in Newark, NJ once for an written exam. On the wall they had all kinds of gruesome pictures taken at homicide scenes and other "mishaps". One of them was an accident that had occured when a person had gotten too close to that 48" fan blade...EEK!

My only real problem is humidity...In the summer here, it is Almost like Miami, not quite, but close. I'd rather be warm and dry than sticky and sticky.
 
Al:

some other things to consider:

Most of the engine's combustion air comes thru those fresh air vents. They are typically the largest opening and offer the least resistance. Most boats have grossly undersized fresh air intakes.I think the current crusader number is around 700 CFM with a pressure drop less than 2" of water. That's a lot of air thru a three inch hose. Bottom line is it is very difficult to have "too much" intake air cross section.

On the exhaust (purge) side, there's the 'from the lowest point' direction that must be balanced with the "hose obscured with bilge water' fact. I found that a good compromise is to ensure the exhaust hoses' inlets are below my slave solenoids as they are the lowest potential ignition sources in my engine compartments.

Read the install manual for more details; if you don't have it, I can email you the relevent section.
 
Excellent points, Mark!
Which leads me to the question of why we don't come up with a induction air system for our marine engines? (i.e., pulling only cooler outside air to the engine's intake) ....... of which could be NO substitute for standard engine bay air replacement!

I've considered this, but the issue for me became over-head clearance while trying to maintain flame arrestor protocal.

There has got to be a way to do it. :)

Wasn't it the old Chrysler Dodge Ram that did this in the 70's?
 
Ricardo:

I think Sonny Hines did that before he exited the custom yacht business. And that was to feed the turbo charged, after cooled beasts he used in his hulls. A true genious on many fronts.
 
Mark, would a hood scoop from a Dodge Charger look OK on my engine hatch?

I know that I could do the install myself! :rolleyes: Well, with the help of the forum, that is!
 
Hey Mark,

I have the TECM 596???? manual for engine repair...I would believe it may be in there so when I get ot the boat I can check...Thanks AL

By The Way: There would be 6 3" hoses total and 4 of them are directly in the engine compartment with 2 powered ones (total 6) blowing out.
 
the one I was looking at has TECM630 embedded in it.

I can't say I remember many mopar details....seem to be better with AMC details
 
While the nose knows is one of the best tools for fume detection
Electronic detectors are a bargain at around $200
 
This thread is 6 years old

Johnny, I hear ya!
I subscribed to this thread back in April of 2010. I was surprised to have recently received a notice of activity!



While there's no rule against posting to an ancient thread............... it's always best to start a new one! :)



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