Can I remove the blower and hoses?

[bsangs]

My 35-3 has a blower and hoses. There's a switch for the blower on the electrical panel, but it doesn't work. Didn't work for previous owner either. I have a Yanmar diesel engine, so don't need a blower, and was thinking of just taking everything out and reclaiming some space. But then I wondered if it would be mistake, because the hoses could be offering some sort of passive ventilation. Before I do anything, thought I'd check here, see if anyone has thoughts about this. Thanks.

 

[acubria]

I removed my hoses and have not noticed any issues, but I have have no idea what I am doing most of the time. I will be looking out for more informed answers and hope I did not make a mistake!

 

[Jaybee]

FWIW I have removed mine on my diesel powered rig. Plan on using a passive system, so the hoses will go back. Considering using solar powered vent.

 

[Christian Williams]

Diesel only: I removed 20 feet of hoses and three in-line blowers. They dominated the engine bay and did very little for air evacuation.

Passive air exchange, cowl vents only, has worked fine for many miles and tropical heat. I do have a third cowl vent on the coaming.

Gasoline fumes, on the other hand, are 4 times heavier than air, hence the need for evacuating the low engine area with blowers before starting, every single time. Spilled diesel doesn't make explosive fumes. Diesel exhaust, however, is bad, sooty stuff. But there should be no diesel exhaust in an engine bay, and so no need for blowers to remove it. If there is diesel smell on board, something is wrong that needs immediate attention.

 

[Loren Beach]

As someone on another sailing forum likes to say: "your boat your rules".


We have upgraded the OEM engine compartment exhaust blower system continuously. A mechanic friend with decades of experience told me that these small engines should have a means to remove ambient heat, and that they were designed to be cooled by mainly the block coolant to about the 95% point, and the last 5% would be by direct radiation. Not a significant amount, but it gets more important as the ambient temperature rises, like on a 90+ degree summer day.
Unrelated but important is that the alternator really hates excessive heat and is mounted at the upper part or top of the compartment. Further insult to injury, as it were, is that a sailboat engine compartment is usually really small.

Seems logical to me, since almost all of these little diesels were designed to live "in the open" in a tractor or as a stationary engine on a skid. (?)

He also advises keeping the block wiped (relatively) clean, as accumulations of dirt/oil film also insulates it. (and makes trouble- shooting a leak a little easier).

So we do have the exhaust blower on whenever the motor is running, and the flexible hose pick-up is at the top of the compartment.
(Totally the opposite as it would be mounted for a gasoline engine, of course.)

As they say on the 'net: YMMV.

 

[Christian Williams]

It must depend on the engine compartment. An engine in a box has heat issues that an engine in a more open environment doesn't.

As it happens, my models have quite open spaces where heated air is free to rise and vent, and the compartment never gets very warm even in extended motoring.

 

[bsangs]

It must depend on the engine compartment. An engine in a box has heat issues that an engine in an open compartment doesn't.

As it happens, my models have quite open spaces where heated air is free to rise and vent, and the compartment never gets very warm even in extended motoring.

Ditto. While the engine compartment itself is not what I'd say easy to access, aside from the front and top, it leads to a wide open area behind it that allows heat to rise and vent. And there are two cowl vents on the transom coaming. I also have a removable access panel door that leads to the Q berth for additional venting. OK, I'm convinced. These hoses and blowers are coming out.

 

[G Kiba]

Yep. Your boat, your rules! I believe the real intention was to prevent a carbon monoxide (CO) explosion from exhaust fumes. That would be from diesel or gas engines.

I kept my fan and vent system intact mostly because it removes a lot of heat from the engine compartment. My compartment is pretty well sealed and has my favorite drawer where I store frequently used tools and supplies. It's located directly above the motor (I think this is unique to the Olson 911). I joke that it doubles as a food warmer but don't store anything flammable there as a precaution.

Vent system was well done by the PO. One dorade on the transom draws air in with an in-hose 4" fan routed to a lower corner of the engine compartment. The exit is another in-hose 4" fan routed from the upper opposite corner of the compartment to the other dorade on the transom. Really well designed with rigid corrugated plastic hose. Both fans are wired to go on when the key is turned on and has a manual toggle switch to override and turn it off. I keep it in the ON position and turn it off when I want to hear better.

 

[acubria]

I should add that yes I did removed my hoses, but I do have 2x cowl vents aft, helping my 6.5hp beast to keep cool.

 

[Filkee]

I connected my refrigerator intake to one of the cowls.

 

[Bolo]

I connected my refrigerator intake to one of the cowls.

Question about your setup. I too am considering removing the blower and hoses from my E32-3 but I want to remove the heat from the refrigerator compressor which is located on the “shelf” inside the starboard lazaret. So I was thinking of running a hose to a position over the compressor and maybe even installing a quiet fan to push the heat through the hose. Maybe even connect the fan to a temperature sensor. But it seems that you are bringing cooler air in the the refrigerator. Is it a passive system or do you have a blower/fan in the mix?

 

[Bobby Steele]

My hoses are shredded. I think they used tissue paper to line them. I had been considering finding a better hose. But that’ll have to wait. For now, we have a stretched slinky.

 

[peaman]

My hoses are shredded. I think they used tissue paper to line them.

Hoses made with thin plastic or aluminum foil supported by a stiff wire coil can't take much abuse, and tend to sag out of shape, which reduces air flow effectiveness. A better solution is all-aluminum semi-rigid duct, which will hold its shape and has a more uniform interior surface for less airflow resistance.

 

[Loren Beach]

If you search the web you can source 3" Vent Hose from reliable vendors like Fisheries. Price per foot varies, but is generally inexpensive. Heat and aging does degrade this stuff, so I plan on replacing it about every 10 or 15 years.
Just one example: https://www.fisheriessupply.com/trident-marine-400-and-402-series-vent-duct-w-wire-black-or-white

 

[JSM]

I removed the blower and hoses from our diesel powered 34-2 six years ago and have noticed no negative effects on engine temp etc.

 

[Bobby Steele]

Hoses made with thin plastic or aluminum foil supported by a stiff wire coil can't take much abuse, and tend to sag out of shape, which reduces air flow effectiveness. A better solution is all-aluminum semi-rigid duct, which will hold its shape and has a more uniform interior surface for less airflow resistance.

Thanks. that was what I had been considering as a replacement, but wasn't sure it'd work. Currently, I'm focused on replacing ancient halyards. I'm thinking they're all original equipment - the wires are frayed and the covering is badly deteriorated.

 

[daynardi]

My 35-3 has a blower and hoses. There's a switch for the blower on the electrical panel, but it doesn't work. Didn't work for previous owner either. I have a Yanmar diesel engine, so don't need a blower, and was thinking of just taking everything out and reclaiming some space. But then I wondered if it would be mistake, because the hoses could be offering some sort of passive ventilation. Before I do anything, thought I'd check here, see if anyone has thoughts about this. Thanks.

I'll add my vote for eliminating the blower. Took it out years ago and never looked back. My theory is that the blower was a design idea left over from olden Atomic 4 times, when positive ventilation was required to remove gasoline fumes.

 

[william.haas]

As someone on another sailing forum likes to say: "your boat your rules".


We have upgraded the OEM engine compartment exhaust blower system continuously. A mechanic friend with decades of experience told me that these small engines should have a means to remove ambient heat, and that they were designed to be cooled by mainly the block coolant to about the 95% point, and the last 5% would be by direct radiation. Not a significant amount, but it gets more important as the ambient temperature rises, like on a 90+ degree summer day.
Unrelated but important is that the alternator really hates excessive heat and is mounted at the upper part or top of the compartment. Further insult to injury, as it were, is that a sailboat engine compartment is usually really small.

Seems logical to me, since almost all of these little diesels were designed to live "in the open" in a tractor or as a stationary engine on a skid. (?)

He also advises keeping the block wiped (relatively) clean, as accumulations of dirt/oil film also insulates it. (and makes trouble- shooting a leak a little easier).

So we do have the exhaust blower on whenever the motor is running, and the flexible hose pick-up is at the top of the compartment.
(Totally the opposite as it would be mounted for a gasoline engine, of course.)

As they say on the 'net: YMMV.

Hi Loren... I use the same approach as you since the engine compartment is quite small and retains lots of heat on the 28. I am curious, what blower model do you have - the one on Danu is so darn loud I dread those hot Chicago summer days when I have to use the thing and listen to it. I have heard that the centrifugal blowers are much quieter than the in-line ones, but at a 3X cost premium it is an experiment I do not want to take on without first-hand knowledge.

 

[Loren Beach]

In theory, my advice will help. In practice, maybe only a little.
I used an (factory installed) axial flow blower (Attwood, IIRC) for decades but really did not like the whine. It worked great and moved a lot of hot air. As part of the 2021 re-fit, we decided to change to a centrifugal blower and on our model the best place to mount it was on the back of the vent fitting on one side of the rear of the cockpit. It is just about as loud, altho a different pitch. It may be a little quieter, but I never have checked it with a dB meter.
Some research probably should have gone into comparing different brands for their noise level. When we motoring along at 2500 rpm, it is not very noticeable, but still louder than the engine. (I have pondered adding a switch, for days when the ambient is under 60 deg. F.)

Also, you might consider how far away from the the exit point the axial flow blower is mounted, also. Further away is better, and it can go anywhere in the hose run.

 

[Mark F]

What's the hot air from? ;-)