Whole Engine Room Air Filter Assembly

I noticed the other day that there was negative air pressure in my engine rooms: the door felt like it was a tiny bit sticky when I opened it. The previous owner had built and installed an assembly to hold blue HVAC roll filter material to screen the top and side of the air inlet in the hull. We have been running for the past two years and almost 1000hrs on the existing filter medium, so I guess it was due.

I removed the filter housings and pulled off the old elements, they are just over 6’ long and the top was 14” wide and the onboard face was 10”. I got a roll of 1” filter material from the local HVAC supply house and swapped out the dirty old material. The old was still transmitting light, but was black and dusty on the side facing outboard while the new was bright blue and translucent. A quick start and run up of the engine on that side showed no lowered air pressure. The door swings open of its own accord while the engine is running now. It would not do so before.

I am guessing that these filters are one reason my Walker AirSeps stay clean and bright red from one year to the next and why I never have any dust in my engine room. I’m sure that this is a homemade assembly since there is no makers name on it. I still have to do the starboard side so if anyone wants pictures, I can take them tomorrow. A 36”x30’ roll was $100, Grainger has it in 1/2” and 1” for much less, but we are only here for a few more days.

I would be interested in this design. Pics and details please...:)

I’m just down the road at Cedar Island Marina in Clinton for the next 5 days or so. You are welcome to come look at them.... I’ll get pics, but there is nothing like seeing things in person.

Totally unrelated but I bought my 34 from Cedar Island Marine back in 92. Nice place.

FWIW those vent panels are still available from SAM's. I bought a set for the 63' MY that I re-fit this Summer. They are obviously two pieces - the top and the front. 10x74 5/8. $222.00 each 14x74 5/8. $290.00 each.

I did exactly the same thing. I built a wood frame and then wrapped it with what sounds like the same material you’re using, I t’s waterproof so when I clean them I just take them out and hose them off, let them dry then reinstall. I would love to see your pictures.

I overstressed my back doing the port side, so I’m taking a couple of days off before doing the starboard side. I’ll post pics then.

Great. Another thing on my list.

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Originally Posted by madhatter1

Totally unrelated but I bought my 34 from Cedar Island Marine back in 92. Nice place.

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Totally unrelated but I kept my 42' Post at Cedar Island Marina 2005-2007.

Good you changed them out.

Here's what mine say. No way doing it at 50 hours but I do get around to them eventually. Yeah, Sam's sells replacements for 2-$300.

Behind that deco molding piece they are just rectangles sandwiched with staples and that material between them. Relatively flimsy.

Sorry pic sideways. Not sure how to fix that.

Attachment 43423
The air filter before removal, notice the color!
Attachment 43424
Filter on the bench with the filter medium loosened for removal.
Attachment 43422
Removing the old filter element showing how it is held in place.

Attachment 43426
Spreading the attachment pieces to remove the old filter element.
Attachment 43425
The filter assembly with the filter element removed.
Attachment 43427
The completed filter after installation.

The new filter material was installed using the large screwdriver to spread the clamping rails and a putty knife/scraper to push the filter material into the gap between the two sides of the rail. The process was not too different from installing a new screen in a sliding door.

OK, that looks different than mine.... My first scoop goes up with filter horizontal and then there's a vertical baffle in front of it. But, it's on the list.

Those assemblies are the same as my 1987 cpmy. They must be factory. Never even considered cleaning or changing them. Another item on the list!

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Originally Posted by Passages

Totally unrelated but I kept my 42' Post at Cedar Island Marina 2005-2007.

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Totally unrelated, but I keep my ‘69 Alfa in my garage.

I suppose someone here stayed in a Holiday Inn Express last night.

I thought so.

Can these be retrofit to an earlier Hatteras? Thinking of my 36C, which does not have any filtration for incoming air to the engine room.

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Originally Posted by Finnley

Totally unrelated, but I keep my ‘69 Alfa in my garage.

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1750 Veloce?

If you have these filters and you can feel resistance when you open the engine room doors at cruise, you need to change the filters. Mine were in place when I bought the boat and it was not until a week or so ago that I noticed that they were restricting the airflow into the engine rooms. Given that you would have to remove the assembly from the boat to wash it and given how easy they are to change, I would just replace instead of clean.

Grainier has 30’x36” rolls in 1” thickness for $45 which will do both sides. It is also available in 1/2” and in various grades of filtration. I got mine from a local HVAC supply house and just took what they had in stock.

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Originally Posted by oscarvan

1750 Veloce?

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Correct sir. Original, 88K mile, 1969 1750 Spider Veloce, red over black. You’re familiar, I’m assuming.

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Originally Posted by Finnley

Correct sir. Original, 88K mile, 1969 1750 Spider Veloce, red over black. You’re familiar, I’m assuming.

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The Alfa was my father's weapon of choice....Berlina 2000, Alfetta GTV 2.0 Uncle had a 2000 Veloce. Moms drove Suds.