Ventilator Hoses / Air Intake

[Pitou]

Strange thing happened for the 1st time in 4 seasons while running offshore in the Albin to troll some lines in 2-3's with occassional 4's all close together. Noticed a burning smell, electrical/rubber, hard to discern. Sure didn't think this could be good.

Ultimately and quickly discoverd the vinyl ventilator hose coming from the stainless air intake vent on the port side that feeds fresh air to the bilge/engine area had taken on seawater and was completely restricted. The hose had been run into the bilge and then zip tied up creating a U shaped loop which had filled with water. Cleared the water and the air flowed free. Decided to check the starboard side as well. On the stbd. the ventilator hose is forward of the bulkhead and had to go in through the hatch under the footrest at the helm. PITA to get to / what isn't in a boat? This hose was restricted as well, not with seawater, but it was pulled forward where it connects to the collector box with another zip tie putting a hard kink in the hose not allowing air to flow. Cut the zip ties on both sides to stop water from collecting on the port side and get the kink out on the starboard. Hard to say if this was factory or the original owner trying to neaten things up, but the zip ties match the rest on the boat. In this case neet should be reserved for your scotch only.

Ran the boat the remainder of the day and for the next 2 and the odor has completely disappeared and air now flows freely on both sides. Check your ventilator hoses. I am glad that is all it took to fix. Boy, just when you think you know your boat you learn a little more. I thought this one was worth sharing.

[Butch]

interesting...how did the water get thru the intake vent...Did you back down in heavy seas? We should all check the hoses!!

[JackK]

Mine has the same setup. I adjusted the hose length so that it no longer had the "U" at the bottom where it was zip tied to the stringer. I never have gotten any odor or sense of overheating. Only my starboard side hose had this problem.

The vent intakes face forward. If running in any kind of chop, they take on some of the spray.

Jack

[Pitou]

The vents need to face forward to scoop the air.
Kind of strange as I've run the boat in much nastier seas, the spray just must not have completely filled the hose in the past. I guess I caught the chop just right, FULL, and with the way the starboard was set up / NO AIR. I probably have been getting a little in that U for sometime, but this time must have caught it just right!

[Mariner]

Is it possible you can change the air inlet setup? It shouldn't be necessary for it to be facing forward for air to get into the engine compartment.

Our air inlets are inside the gunnel and there's no ducting. They're just vents that feed directly into the engine compartment.

[Denis]

Kind of strange, Im trying to figure out what vents you are talking about. The only air intake vents I can remember on my boat are on the inside of the port and starboard side up under the rod holders. I don't think the vents have any hose at all they just ventilate the engine compartment. Could it be that the newer models are that different?

[DougSea]

Kind of strange, Im trying to figure out what vents you are talking about. The only air intake vents I can remember on my boat are on the inside of the port and starboard side up under the rod holders. I don't think the vents have any hose at all they just ventilate the engine compartment. Could it be that the newer models are that different?

The newer boats have vents (on both sides I believe) through the hull below the mid-ship cleats (see the "28 on a lift" post in the pictures section) whereas the older boats have vents under the gunnels as well as a vent on the side of the house. Here's Sonny III, if you look just over the cleat you can see the vents.



Seems like the hull vents would be more susceptable to water intrusion, I assume there's a reason Albin moved them there but I don't know what it is. Noise maybe?

[N4QC]

For some basic background information on air ventilation see:

http://www.yanmarhelp.com/i_vent.htm


Note that one should have an equal air exhaust opening for the air intake opening…

More technical calculations show that a diesel setup requires more surface area of air intake than a gas setup. A turbo diesel requires even more.

Additional air is required to help cool the engine room as other machinery, such as the transmission, generator, etc., need to have the heat they disperse removed.

Local conditions may also play a factor in the amount of air needed in the engine room. These conditions would include water and air temperatures.

Forced air intake and air exhaust can allow for a reduction in the size of openings.

Heed the warning about any ductwork delivering air directly to the air intake of the engine – DON’T…

Calculations can also be done on a CFM basis as well as a square inch basis…

The diesel mantra is: clean fuel, and adequate clean air…

In my case, while under way, my hull vents, port and starboard, are set up to act as exhaust vents. I have a third vent on the side of helm station above the gunwale. This too acts as an exhaust vent, (it was intended as an air intake vent for the diesel). A new source of air intake was built into my steps going from the aft deck to the helm station. This step vent serves as a plenum for an 8”, 1500 CFM (rated) blower which directs air into the engine compartment. I also added a CO detector in the cabin as the engine room is now slightly pressurized.

Hope this helps,

[rt11002003]

Our 1987 Albin 27 Aft Cabin has its air vents in the hull just below the gunnels. It does not have any ducting attached to the vents.

A recent inspection of an Albin 30 Family Cruiser showed its vents inside the cockpit area. I never thought to check for ducting.

I think having outside vents can be problematic, especially if the vessel has a low freeboard or if one is running in a heavy sea.

But, it couldn't be much of an issue I don't hear of a rash of Albin (or other boats) sinkings. Obviously those airducts shouldn't be routed to allow collection/blockage due to water/etc.

I'm trying to understand the air intake vs air/heat exhaust concept when discussing closed engine compartments. In autos, the trend has been toward ducting cooler outside intake air to the combustion area for a number of reasons. The heated air from the radiator and any other heated air is simply exhausted from the open engine compartment, sometimes helped thru special devices. My Audi TT with the 3.2 V6 has a special screened vent at the rear to assist the heated air to escape.

We don't have open compartments in our boats and I've always believed the combustion process used enough air to create a negative pressure in the compartment resulting in any heated air being consumed in the combustion process. When the engine is shutdown then heated air, being at a higher pressure, vents overboard. Naturally using heated air in the combustion results in lower power output.

Gene

[Mariner]

rt,

All the more reason that good engine compartment ventilation is important.

My friend's 19' Sea Ray (4.3L V6) will diesel after running at high speed if you don't run the blower. I thought that changing the spark plugs would rectify that, but it didn't. We've simply found that by running the blower whenever running at high speed, the engine runs cooler and shuts down as it should.

[Pitou]

Thanks N4 / and all. It sounds as if there is no standard for ALL applications when venting the engine compartment. The variables will dictate. Diesel vs. gas / Engine size and turbos and it all makes alot of sense. I run a Cummins 370 Turbo and the intakes are below the rub rail and aft of the mid-ship cleat clamshell forward and exhaust air vents below the gunnel above the rod storage in the cockpit.

I learned alot through this thread in just a couple of days.

[muscrat]

On my 1996, 28, the forward vent on the starboard side had the flexible tubing at the correct length that it appeared to be intended to vent the batterys. It was hanging loose and I refastened it without a loop but with the open end facing down, so that if it did take some water in, it would be directed toward the bilge.. YMMV

[zinbaad]

Ok, glad I am not the only one. I was down in the bilge/engine room and noticed a 5-6" vent hose zip tied to the inner wall filled at the bottom with water. A few feet up was an inline blower that must have sucked in water some how. Vent material broke off and I just drained the water. Should be ok I guess, just didnt make sense the way it was.

[RobS]

Ok, glad I am not the only one. I was down in the bilge/engine room and noticed a 5-6" vent hose zip tied to the inner wall filled at the bottom with water. A few feet up was an inline blower that must have sucked in water some how. Vent material broke off and I just drained the water. Should be ok I guess, just didnt make sense the way it was.

Ed, I wonder if that water in the vent hose was from your rough ride home a few weeks back? Otherwise the surveyor should have picked that up, no?

[zinbaad]

Yes, it probably was from the ride home. There was about 3 cups of water there, I assumed it was salt. Wondering. There is a blower switch next to the steering wheel. I guess it does not go on automatically, perhaps only "on" after a fuel up or when you need to vent out the engine room?? Or is it on always when the motor is running?