OA 420: engine room ventilation questions

[ideabrdg]

Hi All, I'm the proud new owner of an OA 420 Sundeck. The boat and former owner have been involved here in the past: Future OA 42' owner (Hey, Steve). Most recent web site (clearly I need to build my own to continue the tradition): Rendezvous . The boat is in stellar shape and I plan to continue that pattern. I'm new to yachting and have much to learn. To my questions, then.

When Rendezvous has been sitting for several days closed up, the engine room vapors can be strong inside the salon upon boarding. My goals, in order, are to substantially reduce the engine room/mechanical smells in the salon and cabins (with associated VOCs/etc.), potentially improve soundproofing, and explore improved cooling of the engine room space. I've been learning the layout and behavior of the boat, and three observations. First, it seems that there are direct vents into the engine room from the salon; which when not underway would allow for air movement from the engine room. Second, if I close all doors and windows, and open a porthole, there is a substantial volume of exiting the porthole -- indicating that the side channels in the hull may be air intakes for the engine room and substantial channels exist for the air to move through (vents above, but also through the electrical cabinet is strong airflow) the engine room into the salon. Third, there are no seals from the engine room or other bilge spaces to reduce air exchange.

While I expect there are engine room/mechanical odors, is it reasonable to expect that I can substantially reduce them? Is it wise to isolate the engine room and spaces with seals, bulkheads (if required)? I've not manually inspected the blower (yet -- that's set for Saturday) but I've seen the circuit breaker -- should this be run at all times? I've read other posts that suggest that the fiber soundproofing tiles can absorb hydrocarbons and emit them back into the air. Any corroboration?

Thanks for any wisdom, insights and any guidance!

 

[Bacchus]

"First, it seems that there are direct vents into the engine room from the salon; which when not underway would allow for air movement from the engine room"

I am surprised by the statement but can't speak intelligently about an OA. I know my Mainship have no intentional vents between ER and saloon or other living space. That's not to say those spaces are completely sealed and air leak free. I experienced a noticeable diesel fuel smell in saloon immediately after entering after sitting for a period "closed up". There were no obvious residue when I inspected visually, however, a complete cleaning of the bilge & ER using a degreaser solved the issue in my case. My conclusion is that very small amounts of residue can emit noticeable odors when outside air exchanges are not present.

 

[stevemitchell]

Congrats on your new boat!

First, it seems that there are direct vents into the engine room from the salon; which when not underway would allow for air movement from the engine room.

When I owned her, there were no direct vents between the engine room and the salon. That would not be a great situation for a number of reasons!

There were return vents under the salon seating back to air handlers, and other vents for a freezer that was in the galley, etc.

The long black vents on the outside of the hull lead directly into the engine room and are how the engines get fresh air. If the Hurricane heater is still installed, it also gets outside air through those vents.

There are floor panels that sit on wooden beams and supports - the entire salon floor can be removed. There's also a hatch under the salon settee in the storage area. None of those have rubber seals on them, and adding them would probably be a mess of balancing things and ensuring the floor didn't move around. Perhaps the one under the settee is in backwards or not tight?

The "doors" into the engine room in the galley and master stateroom (swinging steps) didn't have any stripping on them either, but that could likely be added pretty easily.

I never really used the powered vents much unless the engine room was really hot.

You could probably add seals to the doors, spray foam in any holes in the electrical cabinet around wires and open items, and improve things.

I don't remember a strong smell of fuel when she was closed up, ever, so there may be something else going on.

 

[ideabrdg]

Thanks Don and Steve. Saturday will be a day of investigation.

 

[Comodave]

Congratulations on your new boat. You need to clean, clean the engine room. To get rid of smells it needs to be clean. Get Peggie Halls book on getting rid of boat odors. It is on Amazon. Just search her name. Then follow her advice. She recommends some products to keep the smell gone. I assume that you have ensured that you don’t have any diesel leaks, correct? I would close up any unused openings between the salon and the engine room, not A/C ducts.

 

[heysteve]

This HVAC putty from RectorSeal (here) also works great for plugging holes in the engine room.

 

[ideabrdg]

Thanks, all. The ER is, to the naked eye, extremely clean and all bilges are dry. I'll share the outcomes as I trace and clean. Thanks again.

 

[learjett2]

I have a 1988 42' sedan, no vents or engine room odors allowed in saloon. Recently noticed the racors are dripping, from the drain valve. just slightly, old O rings the cause. Replaced and no engine room wiffs. Just a possibility.

 

[tagillette]

I know this sounds to simple to work but it does buy a couple tubs of cheap coffee and leave open in salon while vessel is closed up Something about the coffee absorbs odors we have an older diesel vessel no strange odors when entering

 

[C lectric]

Good advice above.
I did this years ago, 20 or 30 yrs ago.. I have forgotten the mfgrs. name and the name of the product but my description should elicit some names. For sound reduction it is a GOOD product.
You likely can also get the name from a GOOD chandler.

My salon floor is mounted on 2" x 3"

My wife and I used to have to almost yell to be heard across the salon even though we were only about 6ft apart.

The foam I used was about 3/4" thick. It had a reflective layer of , I'm guessing aluminum. I installed it on the two engine cover hatches and the noise reduction was noticeable.

For the hatches I used the factory sold hardware securing / attaching the foam securely to the underside of the hatches. It is still present.

I have now done the entire floor underside but over several years. Each installation dropped the noise level to the point we can now talk with just a slight rise in our speaking volumn.

Partly the slow work was because I had to strip a large part of the storage areas of all my tools and supplies to gain access. For the remainder of the installation I used stock flat head SS wood screws, #6 or #8. Don't remember the length but I think 1,25" but check your fit.


I used flat SS FENDER washers that the screws that could easily hold in place.
Just check the screws and washers will hold properly

It only needs a light foam compression to ensure the foam remains in place with a light compression.
You will need a good pair of scissors to cut the foam to size. Fit it lightly and the noise should be reduced greatly.

I also realized that the odours were substantially reduced as I went.

I repaired a fuel leak right at the head in some cases with new fittings The fumes darn near drove me out of the boat making me sick. So check any/all connections for dampness and leaks. I wrapped the connections with the Blue Scot paper towels held LIGHTLY in place with a Tyrap. That helped identify them. Often all it tool was some wrench work.
THe hull side vents faced forward and I eventually reversed several of then so there is pressure when travelling but also suction evacuating the E.R.
Have fun.