E27 ventilation layout?

Ok. I'm getting close to the end of my repower with a diesel in my E27. I have learned a ton about my boat through this experience and just about modified or fixed to some extent most every aspect of this boat (that might be an overstatement but it sure feels that way). And I'm still married so that's good.

First, everything done to my boat prior to getting her seemed to done on the quick and dirty. I've read all the posts I can about ventilation on diesels. So I'll boil this down to a questions I have right now.

My cowl vents vent to nowhere and frankly I have realized that they are probably a source of some leakage since they are just open holes. Any water blowing in just drops straight down. This needs to be fixed asap.

But where exactly should I run the ventilation hose?

Is there a way to modify my e27 to fit some sort of water trap without cutting and modifying?

Is a blower a must have for my diesel if I get the passive ventilation lined up and installed correctly?

Thanks, Jay

This may not be much help. The Coast Guard has regulations and recommendations on this matter. I believe I read that specific rules apply to different year boats. Check online for that and I'm sure you will hear from someone more knowledgeable than myself on this subject.

Thanks, G. I've been doing some searches and so far seems like obviously a must for the gas engines. Still reading and learning. I've got a lot to learn. So far though I think I won't stress out about it too too much.

Just between us: I threw my blower and the vent hoses away. Arguments for them were unpersuasive to me.

If your diesel stops because starved of air, you have a very tight boat.

It doesn't rain here in Southern California and we have no humidity or decent pizza, so my cowl vents go "nowhere" too.

In Virginia, I'd just make a canvas (Sunbrella) bag to put over them, something like a winch cover. (Vinyl cowls need to be covered somehow anyway, or the UV beats them up fast).

thanks, Christian. That helps. We've got great pizza and a good deal of rain and humidity, so I'll cover the vents when at the slip. The rain falls sideways pretty often around here.

I have a 1973 E-27 with a Yanmar Diesel. No blower. The stern cowl vent on the starboard side runs under the quarter berth to a circular hole on the starboard side of the engine compartment. The stern port vent runs at the bottom of the lazarette on the port side of the fuel tank to a circular hole on the port side of the engine compartment. I believe these are 4" vent hoses. The holes on both sides of my engine compartment are the same diameter as the vent hoses. The cowl vent on the bow just ventilates the anchor locker and the "V" Berth.

I learned a trick from a dock neighbor for the rainy season (which lately has been just about non existent here in Southern California), and that is to stuff "Nerf Balls" into the cowl vents when not underway. I have also seen plastic "Hacky Sack" balls used on smaller vents on other boats. This does help keep water water from coming in when it rains. But I do always remove them when underway. Before I started stuffing the vents with Nerf Balls I would get a bit of water that came in through the vents and trickled down the hoses and collected in the well under the engine.

See pic from pages 23 & 24 on Ventilation from Federal Requirements for Recreational Boaters. Not sure how they stand on Nerf Balls and Hacky Sacks.

http://www.uscgboating.org/assets/1/workflow_staging/Publications/420.PDF

Right that would apply if he just upgraded to a GASOLINE engine

Otherwise there are no real regulations for venting a diesel uninsepected recreational vessel.


Thanks,
Guy

Interesting...
I thought the danger was from CO (carbon monoxide)? It is flammable and both engines create it. Right?
Not that I have any ventilation in my outboard driven E27. I do have an aluminum gas tank that is vented to the outside and plumbed with the right CG approved marine hoses.

Non-Flammable Gases

CO is not flammable, but it has no odor, and displaces oxygen which can still kill you. It comes from either the exhaust being pulled back into the boat, or an exhaust leak inside the boat (or burning something like propane or wood inside the cabin without proper vents).

Basically, make sure you don't have an exhaust leak, and keep some hatches open (not just the companionway) when motoring if anyone will be in the cabin so the boat doesn't get the "station wagon effect" and pull the exhaust fumes from outside the stern back into the cabin.

As far as ventilation goes, I can't think of any necessary requirements for a diesel. Passive ventilation would probably suffice. Coast Guard regulations would have the most definitive answer.

G Kiba said:

Interesting...
I thought the danger was from CO (carbon monoxide)? It is flammable and both engines create it. Right?
Not that I have any ventilation in my outboard driven E27. I do have an aluminum gas tank that is vented to the outside and plumbed with the right CG approved marine hoses.

Click to expand...

Macgyro said:

CO is not flammable, but it has no odor, and displaces oxygen which can still kill you. It comes from either the exhaust being pulled back into the boat, or an exhaust leak inside the boat (or burning something like propane or wood inside the cabin without proper vents).

Basically, make sure you don't have an exhaust leak, and keep some hatches open (not just the companionway) when motoring if anyone will be in the cabin so the boat doesn't get the "station wagon effect" and pull the exhaust fumes from outside the stern back into the cabin.

As far as ventilation goes, I can't think of any necessary requirements for a diesel. Passive ventilation would probably suffice. Coast Guard regulations would have the most definitive answer.

Click to expand...

This has been discussed thoroughly in past threads, but the idea of an exhaust powered ventilator for a DIESEL engine has two reasons:
First, it pulls hot air out and any oily fumes from crankcase blow-by along with that air. That's why the intake for that hose run should be near the top of the compartment and near the alternator (a device that dislikes heat).
Second, removing the air constantly will somewhat lower the ambient air temp and your small diesel was designed to lose about 3 to 5 % of its waste heat by direct radiation. This does not denigrate the importance of the heat exchanger, but should not be overlooked when motoring in warmer weather, either.

Upon the advice of an excellent diesel mechanic we run the exhaust blower anytime the engine is running.
IIRC, we are on our second "Attwood" brand axial-flow blower in 20 years. So blower life does not seem to be a particular concern.

Loren

ps: these reasons are important only for operating a Diesel engine. Gasoline engines have completely different safety requirements and deservedly so.

Thanks

Just wanted to thank everyone for their input. This was a very informative thread for me. Thanks.

Jay

Just an FYI about CO from CDC.gov
http://www.google.com/url?sa=t&rct=...=hoBFOKIM4kOocwJaLRuMoA&bvm=bv.80642063,d.cGU

I keep holding a match to this CO2 and nothing happens. What am I doing wrong?

Christian Williams said:

I keep holding a match to this CO2 and nothing happens. What am I doing wrong?

Click to expand...

Yeah I kinda wondered about that idea too.
After all, CO2 is what is inside one class of fire extinguisher...



Loren

CO2 is Carbon Di-oxide

CO is carbon monoxide
C02 is carbon dioxide

I had never heard carbon monoxide as being flammable. Go figure.

-Dean

Blame it on my bifocals

Christian Williams said:

I withdraw one oxygen molecule but it still won't light.

Click to expand...

Oh my.... I missed that molecule completely... OTOH, molecules are rather small and easy to overlook!


Loren

I'm holding a match to my car exhaust, and it won't light either

I'm not sure how to get the CO to light. Maybe have to separate it out and concentrate it? We may have gone off-topic.

CO and flammability

yes, carbon monoxide is flammable- can accept another oxygen molecule and 'burn' to carbon dioxide (CO2)

here is a rather extensive discussion of this issue:

Carbon monoxide is flammable. Mixtures of carbon monoxide and air in the flammable rangewill ignite if a flame or a spark is present. Flammable mixtures containing carbon monoxide andother gases can be ignited easily by heated surfaces, open flames and even by the burning tip ofa cigarette. The serious nature of the flammability hazard is reflected in the extensive flammablerange of carbon monoxide in air (see Table 1, below).
Table 1: Physical Properties of Carbon Monoxide


Do not attempt to put out a fire involving carbon monoxide unless the flow of gas can be stoppedbecause a more explosive mixture of gas and air may form. To reach the valve to shut off theflow of gas, use a carbon dioxide or dry chemical extinguisher. Use a water spray to keep thearea cool and to prevent ignition of other materials. Do not use a water jet.
Carbon monoxide is chemically reactive at temperatures over 90 °C. This reactivity andchemical incompatibility can be of great concern in laboratories and process operations wherecompressed carbon monoxide is present (see Table 2 on the next page).

I didn't know this either. the flammable range will kill you before you burn to death, though.

steve naulty MD
ericson 35-3 'anodyne'
shadyside MD

Huge flammability range!

Wow, that really is a big flammability range. I'm not sure what percentage will suffocate you, but it also explains why my car exhaust didn't erupt in flames. I'd have to capture the CO, then light it. So I suppose CO build up in the cabin could easily remain in that 12-74% range long enough for an eventual spark to ignite it. Another reason to run the blower while the engine is operating, regardless of fuel type.

Thanks! I learned a lot more, and don't feel as bad about re-powering with a gas Atomic 4!

-Dean