Dorade vent engine cooling E-28

[DanielW]

I've noticed that many photos of E-28's out there show that they are fitted with two dorade vents either side of the cockpit towards the rear of the boat (see photo below which I found via Google and kudos to whoever owns Endurance - she's a beauty). One vent points forward, one points backwards. I'm assuming that these are to facilitate engine bay cooling. My E-28 has closed round covers on the hull cut outs and inside there are black hoses leading into the engine bay. If the dorade vents came fitted as standard or were supplied to use as and when necessary then mine are long lost by one of the POs. I suppose I could source dorade vents of the right size but are they really necessary? I've had the boat for four years now and have never had an engine overheating issue; I live in the topics as well so its pretty much 30 degrees all year round here. My other thought was to fit some small solar vents here to pump air in and out. These would be a neater installation but again, is it really necessary? I know that I should probably just work on the basis that if it aint broke then don't fix it but It's bugging me that Ericson saw fit to install the holes and hoses and yet on my boat they are covered therefore rendered completely useless.

 

[Frank Langer]

You are lucky living in the tropics this time of year! As I understand it, venting the engine compartment is important not only to avoid the engine overheating, but also to keep the temperature down a bit, because components like the alternator don't like excessive heat. Many boats (and yours might too) have an exhaust fan/blower motor operated by a switch on the engine panel to draw hot air out of the engine compartment and suck cooler air in to moderate the temperature.

In your post you state that the "dorades" are covered on your boat. In looking at the picture you attached, I see one plastic/rubber vent on the port side and one on starboard at the back of the boat. Normally there would be a 3 1/2" hose attached to the inside of these and leading into the engine compartment to promote the air flow. Does your boat not have this?

Either way, I think it's a good idea to vent the engine compartment. If I've been motoring for a while, I sometimes even hold open the companionway locker cover for a few minutes to allow warm air to escape from the engine compartment inside that locker.

Venting would be even more important if you have a gasoline engine rather than a diesel, because gasoline is more flammable than diesel. For gasoline I understand that you need to vent the engine compartment for about 5 minutes before starting the engine, so any gas fumes are gone and not ignited by a spark when starting the engine.

I hope that helps. I'm not a mechanic, so the pro's might have additional or better information.

Frank

 

[Loren Beach]

Whether an Ericson Yacht or my Olson, the factory setup was very similar.

One vent to allow fresh air to be drawn into the engine compartment -- diesels have a voracious appetite for air.

The other vent would be plumbed with light-weight hose to an exhaust blower to pull hot air out of the engine space and also any oily odors. Given our original equipment diesel, this means there would be some crankcase vent odor, and any time our blower is off we can indeed smell it.
Note that this intake location advise is for Diesel engines only.

I have replaced one "Attwood" Turbo model blower a number of years ago when the old one died. My impression is that they can last a decade+, and, the new ones are not expensive by "boating cost standards".

Our mechanic advises to have the exhaust hose intake located neat the compartment top and closer to the alternator area, since they dislike heat (shortens their life).

And, to run it all the time the engine is on. Which we do.

I have both external vinyl vents pointed downwards to shed rain.... living in Oregon, well, you know how it is............
:0

Sidebar: If you sailed any other brand of boat, the advice would still be the same, FWIW.

Send some of that tropical heat our way, please!


I put the word attwood into our site search box and got this and there might be some others. (Thinking up a key word is a good way to get focused search results.)
http://www.ericsonyachts.org/infoex...3602-engine-compartment-cooling&referrerid=28

Loren

 

[Christian Williams]

You know, my M25 seems to make very little heat. Since the compartment is pretty well vented with the two cowls on the transom, I tossed the nonfunctioning blower. Actually, I didn't know diesels needed one, although I now see it makes sense to move the air if the engine room is tight. No smell to speak of, even from the exhaust, which is belched under the stern.

We have cool water here, in the fifties now and high sixties in summer even though its "southern" California. Six hours of motoring at 6 knots and never above 160F.

Good to know what the blower was for, and to keep an eye --and nose--on the current setup.

 

[DanielW]

Wow, okay, I think I need to get some fresh air into that engine bay then. I have been doing some research around this and realize that the diesel guzzles a lot of air. I understand that there has to be adequate air in to compensate for the air going out and will utilise the existing holes and hoses (currently blocked). My initial thoughts from some weeks back were to fit two solar vents like the picture below, one on each side (I find these more aesthetically pleasing and less likely to get damaged when they are inevitably stomped on). One will draw air in and the other will suck out. These can shift around 400-500 cubic feet of air an hour. Will this be enough for my beta 20? I assume that additional air will be sucked in via gaps around the hatch and companionway steps; which is where the current air flow is no doubt sucked in. Alternatively, should I just fit the dorade vents and install a blower?

 

[DanielW]

Just checked the spec on the Attwood website; their blowers shift between 5,500 and 7,200 cubic feet of air per hour which is more than ten times the amount that the solar vent does so I figure I need to be fitting the Attwood Turbo

I'll post more as this particular project progresses.

 

[DanielW]

Just found this online :

http://www.ybw.com/forums/archive/index.php/t-47051.html

Nothing but confusion, contradiction and bitching.

Makes me thank my lucky stars I have an Ericson and can benefit from the advice of such awesome people as your good-selves!

 

[PDX]

Jabsco also makes an engine room fan you might be interested in. 4" hose, 250 cfm, 5000 hr life. It comes in bulkhead mount or non bulkhead mount styles.

http://www.xylemflowcontrol.com/files/artdoc1851.pdf

 

[Rob Salinas]

Boats with gas engines in closed compartments built after Aug.1 1980 must have a powered vent system, those built prior must have natural or powered. Also boats with closed fuel tank compartments built after Aug 1 1978 must have natural or powered vent in fuel tank compartment. Those are USCG requirements, not sure about Singapore regs, but you cant be too safe. I have two dorade vents on the transom, foward pointing is natural vent,aft
pointing is connected to engine blower, which I just leave on when motor is running. I know someone who was told by CG Aux to turn one vent foward, both were aft facing, during a VSI.

 

[DanielW]

Boats with gas engines in closed compartments built after Aug.1 1980 must have a powered vent system, those built prior must have natural or powered. Also boats with closed fuel tank compartments built after Aug 1 1978 must have natural or powered vent in fuel tank compartment. Those are USCG requirements, not sure about Singapore regs, but you cant be too safe. I have two dorade vents on the transom, foward pointing is natural vent,aft
pointing is connected to engine blower, which I just leave on when motor is running. I know someone who was told by CG Aux to turn one vent foward, both were aft facing, during a VSI.

Singapore doesn't have a great deal of regs when it comes to "pleasure boating". I'm going to install a system as advised on here, namely one passive vent to let air in with a forward facing low profile dorade vent and one active vent with a blower installed (I'll see what's available here in Singapore) and connected to an aft facing low profile dorade vent.

 

[unequaltee]

Blower

Be aware the axial flow fans can be very noisy. I fitted one that made more noise than the 30 HP diesel it was venting! It lasted about a mile before I cut the wires!
The quieter (but more expensive) are the snail like drum fans.
To reduce any heat in the engine compartment has got to be good. I notice on my Sadler the heat from the engine bay warms the cabin (not a bad thing here in the UK most of the time) But less desirable in warmer climes.
Ian

 

[celtic sea]

As stated in post above the CG advised one vent should be pointed forward, on my E27 the PO has them both facing aft. I haven't checked but does one not have a hose connected to it? My blower works fine and from the cockpit locker I can see the hose/tubing running back to the vent, which one should be facing forward?
Guess somehow I'm going to have to try and see back there if only one has the tube connected or they both have tubing.
Just another item on the list, at least this ones easy!

John
Celtic Sea
1973 E27 with A4

 

[DanielW]

90% of the way there

I'm almost done with this job, the inline blower and hosing ready to go. My last hurdle is the type of vents I use to get air into and out of the engine bay. I don't want to use the dorade style vents for aesthetic reasons, I am looking at clamshell type vents like that pictured below. Now, my concern is rain and/or waves, spray etc. getting into this and therefore into the engine bay. Any suggestions on how this can be avoided? Anything to be done with hose angle (create a loop) to ensure water always runs out of the vent? Just live with it as the water ingress will likely be minimal and will end up in the bilge and being pumped out anyhow? All suggestions welcome.

 

[Rick R.]

Blower? We don't need no stinking blowers!

Both vents ducted to engine compartment but no blower and no problems here in hot Florida.

 

[DanielW]

Both vents ducted to engine compartment but no blower and no problems here in hot Florida.

Any water ingress? It must rain occasionally, even in sunny Florida.

 

[Starduff]

Dorade vents E-28

I keep the port side forward and slightly down, while the starboard is facing aft and slightly down (keeping down any rain intake.) No problems in seven years on my E-28 with a universal 10HP diesel.

Richard
"Polonius"