The Science of Smell

Hi All,

After have owning the good ship for about a year and a half, it' time to talk about the science of smell. As you may recall, I asked about the "old boat" smell I thought I had and the white dusty appearance on all the shiny woodwork in the cabin. Since that time, I have replaced all the floorboards in the engine room (which were diesel soaked), washed down the walls several times, replaced all head plumbing and have a new holding tank (never did have the nasty head smell) and generally keep her ship shape and clean. I presently have fixed all water leakage into the cabin of the vessel. I'm in the Pacific Northwest (very wet), we have heaters and a dehumidifier on all during the winter months.

So... here are some questions I ponder and wonder if anyone else has these symptoms or can explain the science.

When I open the back door, that "old boat smell" is very prominent. After I'm in the boat for 5 minutes, I don't smell a thing. I smell the galley towels... OK. The pillow cases... OK. Hang up my coat and stay for the night. The next day when I leave the boat, my coat smells like that smell when I first walked in. Anything I take out of the boat has that smell; clothes, and even plastic bags! Baggies smell worst of all. What is in the air that can turn a baggie into an "old boat " smelling plastic thing? I can hang my jacket in the garage and 3-4 days later the smell is gone. The plastic bags are ruined for life. Perplexing to say the least. My wife thinks I may have a nose problem as the smell doesn't affect or bother her like it does me.

Before you suggest all manner of cleaning scenarios... I've read them all and tried many. I thought for sure after I yarded out the soaked flooring and the head systems that would do it.

Discussion? - Dave

Yup.

First, you get used to a smell so why after 5 min you don't smell anything. Beyond that not sure what your smell is. On my boat I know that the smell comes from water in bilge and being closed for a week under the sun, if I vent the whole boat and clean the bilge smell is gone. But yes, when I open the door after a week away, there is that smell that bother me.

L

Most people get used to a smell in a few minutes and then their brain sort of stops registering it. This is mechanism that allows you to detect new smells or if the original smell changes.

If you go out of the boat for a few minutes and then back in, you will register the smell again, but the sense of it will likely fade more quickly.

Do you clean the surfaces with an anti microbial solution (i.e bleach)? Are you bilges dry?

Women usually have more sensitive sense of smell than men. Something to do with protecting their children from pathogens.

How much ventilation do you have going on while the boat is closed up? Maybe put a couple of solar powers vents in. One sucking in air and another at the other end of the boat exhausting air. We had a 46’ trawler that had a bit of smell, not bad but annoying, the 2 vents took care of the problem. Of course I did all the cleanup stuff like you have done first.

Consider both angles to the smell. It's either some smell you inherited on the boat that is from the boat itself or it's some product used to try to rid the boat of the smell. The fact that every item you take on the boat picks up the smell is really disturbing because of the worst case things it might be.

Are you feeling any symptoms after smelling it? Have you found anywhere on the boat you can go and get away from it?

I have encountered something similar in my shop at home. It's used primarily for car and other machinery repair and restoration, and has a bunch of old car parts on racks, and a couple of cars. It used to smell a lot when you would first step in, but that has diminished over the years. But the part of your description that caught me is how the smell sticks to clothes. I can be working in the shop for several hours, but not working on a car or otherwise doing anything messy. But at the end of the day, my tee short will always smell like the garage. So it's picking it up from the air.


My assumption has always been that it is fumes and out-gassing from the old greasy parts. I have also found that any spilled diesel will smell forever if you just wipe it up, even if there are just drips. You have to clean it up with cleaner to get rid of the smell.


Wouldn't it be great to have a smell meter that you could use to locate the source? Or better yet, a FLIR smell imaging camera?

An Ozone generator should clean up the smell, even if it is wood rotting somewhere.

Have you tried replacing the cushions in the cabin? They can hang on to old smells.

We solved ours with ventilation.
Turns out, the bilge and the engine room are what cause most smell: the moisture, the diesel, the oil, holding tank, etc.
We installed a quiet ventilation fan that runs continuously, pulling air out of the engine room.
We blocked all external vents into the engine room, so the only way air can get in is through the living space.
Air is pulled into the salon through a small hole above the helm, this fresh air then moves down into the cabins and enters the bilge below the berths and through openings we made to the engine room near the heads. The air then moves through the engine room to the ventilation fan and is pushed out.

It works amazingly. The hard part is figuring out where all the openings are to the outside. We wanted the fresh air only to come into the salon near our heater/A/C. This meant we had to install traps on all the sinks because air was coming in the drains, and find a bunch of other random openings from the PO. There were six engine room vents, so we had to make covers for five of them that we put on when we're not moving. We can control where air enters the engine room by making or blocking holes between the living space and the ER. For example, we have larger holes near the heads because that's the air we want to get rid of.

We used a fantech 110 CFM ventilation fan because it's quiet. We installed a variable control so we can turn it up or down if there's moisture we want to get rid of.

A bonus of the system is that it keeps the engine room at a perfect temperature in the winter because the tempered air from the salon ends up moving through there.

Thanks for the replies! I am considering a fan from the engine room to outside. My bilge is dry and clean. In fact when I go down there, I smell ... engine. I’m an old car/ heavy truck garage mechanic, love that smell! ?

Dave_E said:

Thanks for the replies! I am considering a fan from the engine room to outside. My bilge is dry and clean. In fact when I go down there, I smell ... engine. I’m an old car/ heavy truck garage mechanic, love that smell! ?

Click to expand...

I would consider an air check as at least you can then narrow it down to type of cause.

FF said:

An Ozone generator should clean up the smell, even if it is wood rotting somewhere.

Click to expand...

X2 on the ozone generator. It will kill all the bacteria mole etc then you can start from a clean slate. Should not be used regularly or while inhabited.

Wow. 13 posts and no Peggy? I know OP said he read everything but in case...The New Get Rid Of Boat Odors...

I had "the smell" and chased everywhere as a new owner...the strange solution to my exotic problem was to clean, REALLY clean the bilge and then do it more often
dummy. Smell gone. It did take a month of use and good airing out, putting cushions in the sun for a few hours, to really get it out but not an issue after that. As long as I clean the bilge. Smells like that nice mixture of old boat smells now...32 years of wood, machine, etc. Not much smells better to me.

I had that problem in a hunting camp this year. The camp was closed up most of the summer except for a few weekends.
It was so bad it would soak in your clothes and the deer would smell you anytime they got within 100 yards. I ended up getting an ozone generator.
Set it several times before I went hunting. Within a couple of weekends the smells were gone.
Worth a try for 100 bucks
https://www.amazon.com/Airthereal-M...2&sr=8-2-spons&keywords=ozone+generator&psc=1

I have a theory that what some folks are calling "old Boat smell" is actually rotting wood. Everytime I smell that smell, I almost always find a small leak and/or a soft deck nearby.

I'd still recommend talking to a professional odor detection and removal service. Although they specialize generally in buildings, some of those near the water do have boat experienced. Just google "Your town odor detection and removal." I have used such services over the years and all but one time they were very successful and that one time they came back at no charge and solved the issue then. I have not used them on a boat, but did talk to someone who did successfully. Problems I've encountered have included mold, air conditioning systems, plumbing, dead animals, termites and rotten wood. Once you've tried, unsuccessfully, then it just seems wise to turn to someone more experienced. Remediation of this type isn't cheap but then what's the cost of a long term smell and continuous unsuccessful searching for it?

West did you consider your engines air requirements?

Hi Dave_E and Firstbase,

My guess is Peggy Hall is simply bored with responding to this question for the bozillionth time. Yep, buy her book, do as she suggests, and "old boat smell" is gone. No mouse milk, no magic elixirs, no ozone generators, nothing but sound cleaning and continuing maintenance practices to banish odors for good.

While everyone has a different tolerance for odor, in my opinion, the only way for a boat to smell is not at all. Just as I won't own an ugly boat, I won't own one that smells of ANYTHING. Get rid of odor, and I'm a happy boy.

Regards,

Pete

On Peggie’s recommendation I started selling Pureayre in my store. Got a couple of positive comments from customers. The trick seems to be to really soak the surface. A light mist isn’t enough, at least not for cat pee.��

bayview said:

West did you consider your engines air requirements?

Click to expand...

Yes sir. We don't keep the vent covers or the exhaust fan on when the engines are running, just when we're at the dock, or if we're at anchor for a while.
We live on the boat, so good ventilation is pretty necessary. I don't want to be breathing all that crap from the engine room anyways.

Westiculo is right! Ventilation is the answer.
I have a wood boat. I should have the boat smell in spades, but don't because I ventilate. My boat has 5 wt bulkheads and 6 separate bilge areas. I use a bilge blower with a speed control to run at a very slow speed, all year. In big bilge areas, I use 4" 12v dc computer type fans to circulate the remote places. Besides keeping the bilge dry, the smells that originate in the bilge area go directly out. The incoming air keeps the boat air fresh. I don't think it greatly affects my heating costs.
Where my diesel stove and pellet stove exhaust, I have triple wall pipe that brings in fresh air in the middle section, warming it with the exhaust heat. It comes out in the hottest area, right above the stove.

LaBomba said:

X2 on the ozone generator. It will kill all the bacteria mole etc then you can start from a clean slate. Should not be used regularly or while inhabited.

Click to expand...

Ozone can degrade hoses and rubber parts. FYI

BYNW said:

Ozone can degrade hoses and rubber parts. FYI

Click to expand...

Peggy's Book....Section IV...."A few Words About Ozone Generators"

Firstbase, Self-Appointed Exec. Assistant to Peggy Hall

HopCar said:

On Peggie’s recommendation I started selling Pureayre in my store. Got a couple of positive comments from customers. The trick seems to be to really soak the surface. A light mist isn’t enough, at least not for cat pee.��

Click to expand...

After my Poop-A-Palooza incident which ended with 25 gallons of holding tank contents sloshing around my bilge and into every nook and cranny we cleaned...excessively. Knocked it down somewhat for a day or two but smell came back. Bit the bullet and Pureayre'd twice. Smell gone. As Parks mentions, Pureayre works.

Again, thanks for the replied and the knowledge of folks who have "been there, done that". I did find a small leak in my port fuel tank and it has been accumulating in the hull for who knows how long. We're fixing the leak soon, but that leaves the interior of the boat... all the cushions etc. that have been exposed to diesel air for who knows how long over all the years. Since we seemed to notice things weren't so bad in the summer (when we keep things opened up)... I'm going for the ventilation first (and of course fix the pin hole leaks in the tank).
Thank you all.

Dave

Our 42' Cape Flattery Trawler is set up over winter with a dehumidifier, two bilge fans, one galley fan, and one for the aft stateroom. We keep the sun out with covers/shades and we have a ceramic heater that keeps temperature around 50 F. Also we have the engine room hatch open. This keeps the boat humidity down nicely. And yes, clean bilges that are dry as you can get them, will cut down. I might suggest, too, that you open all galley, stateroom and v berth cupboard doors to keep them circulating.

Some odor eaters might also help.

Boat smell seems to be worst where you have damp conditions. Usually this is caused by water in the bilge which can be unavoidable in wooden boats. When this dsmp condenses onto a cold surface like the hull and topsides, there is likeky to be mildew forned. Unpainted wood can be particularly vulnerable to this. A solution which has worked well for me over the years is to wash the surfaces with a mixture of hydrogen peroxide, wzter and mild soap ie washing up liquid. This gives a fresh smell to cupboards and clothes drawers. Spraying cushions regularly with a diluted solution of Comfort clothes freshioner will also help. The bilge fan extractor idea already mentioned is good too.

In my five-decade-plus career on boats, I have had the pleasure to work on a few very old vessels. 1896, 1906, 1909 are some of the oldest with Wander Bird 1881, being the oldest.
I'm sorry to say that smell is most probably dry rot in wood somewhere in the boat you can't access easily.
If you can access it, after determining that it is not a structural problem, any good exterior wood preservative will kill the rot and stop the smell, at least for a while.
I hope I'm wrong, but I thought I'd throw it out there in case none of the other suggestions solve the problem.

Yes to pure ayre

HopCar said:

On Peggie’s recommendation I started selling Pureayre in my store. Got a couple of positive comments from customers. The trick seems to be to really soak the surface. A light mist isn’t enough, at least not for cat pee.��

Click to expand...

After reading Peggy’s book, I did all of the things for odor she recommends including use of Pure Ayre.

Key is cleaning first, then spraying.

Boat is beautiful with regular maintenance