Winter storage in NE- full or near empty gas tank??

[DuxKing]

storing a 275 Grady White with 1 350 Yamaha . in Massachusetts. Should the gas tank be as long as possible or should it be filled up prior to having it winterized

Any other tips i should do before dropping off at Bayside Marine (Duxbury MA) for winterizing and storage.
thank you

 

[Legend]

I have always filledl mine - I have heard lees a chance of condensation developing but for most years it has been a benefit since gas prices used to go up every spring just in time for boating This question has been asked and you will see many different responses with the opposite view. I'm on my 3rd Grady and this has always worked for me with no issues.

 

[seasick]

In my experience, I try to leave my tanks somewhat empty but sometimes that means 50 gallons of gas is still in the tank. I treat it with stabilizer and that's it. To store empty is ridiculous. Do you pump out the gas or run till its empty and get towed back?
Filling is not necessary and doesn't make a lot of difference except in areas that have large temp swings during the day and high humidity. I can't see filling a tank with goos gas and then find out in the spring tha the gas is bad from water intrusion or a bad load. That means you have to get rid of a lot of gas.
Folks on this forum will argue their opinions for all options but with 14 years on one boat and 3 on the other, I haven't had any problems.
After I start the motors in the spring and burn of ant storage oils, I replace filters and then add new gas to freshen up what was left over from the last season

 

[Finest Kind]

I'm with seasick. Owned 2 Gradys since 1989 and NEVER filled the tanks during winter storage in New Jersey...never had a problem.
I still don't fill the tanks during Summer storage in FlaDa nowadays. I keep them as close to empty as possible and hit them with an overdose of Stabil and Startron on the last use before storage, then fill up the tanks with fresh gas upon re-commissioning after storage.

 

[Salmondogs]

Always store with full tanks ESPECIALLY IF IT'S AN ALUMINUM TANK! Aluminum attracts condensation like crazy, so if you have high humidity at any point during storage there's a good chance moisture will get in through the fuel tank vent and condense on the exposed aluminum. I've seen it a lot here in the PNW. Worse case I've delt with was a guy who lived in a valley where humidity was always really high, we pumped 10 gallons of water out of the bottom of a 100 gallon tank after sitting for one winter. Good fuel that has been properly stabilized wont go bad over the winter.

 

[seasick]

Always store with full tanks ESPECIALLY IF IT'S AN ALUMINUM TANK! Aluminum attracts condensation like crazy, so if you have high humidity at any point during storage there's a good chance moisture will get in through the fuel tank vent and condense on the exposed aluminum. I've seen it a lot here in the PNW. Worse case I've delt with was a guy who lived in a valley where humidity was always really high, we pumped 10 gallons of water out of the bottom of a 100 gallon tank after sitting for one winter. Good fuel that has been properly stabilized wont go bad over the winter.

If that tank had 10 gallons of water in it, I doubt it was from condensation, at least not most of it. In just about every case of excess water in a tank I have seen in the past several years at my club have been due to water intrusion and possibly in 2 cases, a bad load of gas. Just about all of the water intrusion caused were traced to bad gas fill cap seals (o-rings)
Secondly aluminum does not attract condensation anymore than any other material. Condensation is a function of the temperature of the tank and the gas, the temperature and humidity of the outside air and the dew point.

 

[DennisG01]

Secondly aluminum does not attract condensation anymore than any other material. Condensation is a function of the temperature of the tank and the gas, the temperature and humidity of the outside air and the dew point.

But it does change temperature faster than another metal... thinking that might be a variable. However, I'm going to make an assumption that Salmondog was referencing the difference to a plastic tank.

As Seasick pointed out, there are merits to both sides of the argument. For reference, I'm a "fill it up" guy. No issues for me.

 

[seasick]

The whole process of condensation and tanks is probably a lot more complex than I understand.
I'm too cheap to be a fill it up guy although doing so or nor doing so can be likened to buying oil futures. If you think gas will be more expensive in the spring, buy your gas now. If you expect gas to be cheaper, don't fill up.

One piece of advice that I offer is when you buy gas from a marine gas station and that station is located in an area where they don't pump a lot or any gas during the off season, when spring arrives, don't be the first in line to buy gas. It probably has been sitting all winter

 

[Salmondogs]

If that tank had 10 gallons of water in it, I doubt it was from condensation, at least not most of it. In just about every case of excess water in a tank I have seen in the past several years at my club have been due to water intrusion and possibly in 2 cases, a bad load of gas. Just about all of the water intrusion caused were traced to bad gas fill cap seals (o-rings)
Secondly aluminum does not attract condensation anymore than any other material. Condensation is a function of the temperature of the tank and the gas, the temperature and humidity of the outside air and the dew point.

We service the boat every year, before and since this incident, we do the winterizations in the fall and the de-wins in the spring. Since that winter he religiously fills his tank before he brings it to the shop for his winterization and has never seen a problem since and we haven't done a thing to the boat. This was the worse case I've ever seen and he lived in an what you could call an extreme environment and it was a warm winter for us so the relative humidity was high all winter. But every year we have a couple boats that come in with partial tanks that have had water intrusion due to condensation and without exception they always have aluminum tanks.

I used to be the shop foreman for a contractor that serviced aluminum patrol boats at my last job. We were required to service the boats every 100 hrs or every 90 days. In the fall and spring it was common to find an inch or more of fresh water in the rear deck boxes from condensation on every boat that was stationed west of the Cascade Mtn range. Here in the PNW we live in the land of aluminum boats and condensation is a constant battle. Cabin mold is much more common on aluminum boats, especially if there isn't any type of carpeting or insulation in the cabin.

Finally, although aluminum is considered a good conductor of heat compaired to other metals, it takes much longer to warm up from ambient air than a composites do. Thus in high humidity conditions, ambient moisture in the air will condensate on an aluminum surface for a much longer time than a composite will due to the temperature difference between the ambient air and the aluminum.

 

[Salmondogs]

After I read that it sounded somewhat hostile. I apologize, not my intention. I'm just trying to impart some of my experience. I agree that getting rid of a load of bad gas isn't cheap but I've never seen good stabilized gas go bad over a winter and servicing and or replacing fuel system components isn't a dollar menu item either! Oh and for sure get the best fuel you can, non-ethanol if possible and definitely from a place that sells a lot of fuel so it never has a chance to go bad and the storage tanks get "flushed" frequently.

 

[seasick]

I didn't sense hostility and I did expect a lot of disagreement as usual on the topic. I have yet to see a scientific study on condensation rates in gas tanks and how the variables like humidity and temperature changes affect the rate of condensation. What I am pretty sure about is ethanol blended gas does absorb water vapor, about 1/2% by volume. In 50 gallons of gas, that is a quart of water. In my sometimes simplistic method of logical thinking, that means that if you add 50 gallons of fresh and 'dry' ethanol blended gas (10%) and there was a quart of water on the bottom, that quart will be absorbed by the E10 and burn off in the motor. Without E10, where does the condensation go? It drops to the bottom of the tank.
Using that logic ( maybe questionable) it seems that you would have more condensation water in a tank of non E10 than one with.

Now to be fair, since E10 does absorb water vapor, there is the variable of whether your load of E10 is as I say 'dry' . The marina tank if it has water in it, will also contribute water to the E10 gas.

I believe that for every 100 folks who fill the tank, 100 don't. For those 200 cases, only a small percent have problems in the spring with water and the argument about E10 contributing is moot since all gas in my boating area is ethanol blended.

Although non a truly controlled experiment, I had a boat with a 135 gallon aluminum tank that had 70 gallons of E10 stored on land and shrink wrapped for two years straight. I tested the tank with a stick coated with a water detection dye and there was no water at all. I ran on that gas for weeks while I worked on all the other issues

 

[DennisG01]

One thing to add to the discussion about ethanol and water in the gas... with ethanol in there, you can get "phase separation". This is where the ethanol, heavier with water, falls to the bottom of the tank. The ethanol is the piece that gives the gas it's octane. So with PS, you end up with water-soaked ethanol at the bottom of the tank and regular fuel that is very low in octane above it.

Plus, the water that is now bound to the ethanol will NOT get burned by the engine since it's too large to go through the fuel/water separator. If there were no FWS, you'd end up with large water molecules that can cause damage. A proper fuel stabilizer can help mitigate this problem - but that's a whole 'nother discussion!

The fact is, condensation can and does happen. That's just plain physics - and the less air space in the tank, the less condensation. Whether it happens enough to cause a problem is the real question. And, truth be told, there's just too many variables to say, definitively, whether there will be enough (or any) condensation to cause issues in a certain scenario.

"Best practice", is to go completely full or completely empty. But whether that's needed, depends on all of those variables - and that's why we have opinions - which are all good

Salmon... I also didn't see any hostility in your statement.

 

[Doc Stressor]

Completely full or as empty as possible with stabilizer added. Stabilized fuel is good for at least a year. I recommend StaBil or the Chevron product.

E10 doesn't suck water out of the air to any great extent. The water accumulation is due to condensation except in cases where there is water intrusion into the tank. With a full tank, there is a minimal exchange of outside air through the vent because of the small gaseous volume in the tank. With a nearly empty tank, any accumulation of water is typically absorbed by the dry E10 when you add fuel the next spring. I've always used the full tank approach since 1975 that includes winters in New England and summer in Florida.

No fuel additive can prevent phase separation. The best way to get rid of it if occurs is either to pump out the tank or add a large amount of fresh E10.

People who have gotten away with storing partially filled tanks are usually those who store their boats in cold climates. Cold air holds less moisture than warmer air. Phase separation is not a problem until it happens to you.

 

[ScottyCee]

Variety being the spice of life, I will chime in as the guy that drains the tanks at the end of the season - I run low before de-launching and then pump the rest out into cars, lawnmower, etc., until it's gone. In the spring, I also put a small amount of fuel, a quart or two, into the tanks and pump them out again. Then I change my fuel/water separators as homage to/battle with the evil condensation gods...

 

[Toothpick 10]

There seems to be a million different opinions on this topic and everyone seems to claim good success with their method. Here's mine: I'm usually around 1/2 full and I put in a heavy dose of stabil and startron. Therefore, when I fill the tank before splashing in the spring, I will have 1/2 tank of fresh gas, and my stabilizing products will be diluted.

 

[Doc Stressor]

There is no reason to dilute the stabilizer. It is mostly naptha carrier (which is basically gasoline) with a small amount of active ingredients. I use stabilizer year-round in case the boat needs to be laid up for a while.

 

[seasick]

As expected. many opinions.
Doc, I need to understand why your theory is that an empty tank doesn't have as much condensation as a mostly full one. I would think that in a partially full a surface of liquid gas which is the same temp as the tank walls will have the same amount of condensation. The main factor is the relative humidity of the air in the tank, it's temperature and the temperature of the liquid and tank surface.
I didn't major in thermodynamics so maybe I just don't understand the mechanics.
Can we agree that an empty tank can also collect condensation?

 

[SkunkBoat]

The answer is yes.

 

[SkunkBoat]

As expected. many opinions.
Doc, I need to understand why your theory is that an empty tank doesn't have as much condensation as a mostly full one. I would think that in a partially full a surface of liquid gas which is the same temp as the tank walls will have the same amount of condensation. The main factor is the relative humidity of the air in the tank, it's temperature and the temperature of the liquid and tank surface.
I didn't major in thermodynamics so maybe I just don't understand the mechanics.
Can we agree that an empty tank can also collect condensation?

I think he means;
If the tank is empty there is no temperature difference to cause condensation. The aluminum matches the air temp quickly. Half filled, the fuel stays warmer or colder longer than the air and the tank matches the fuel temperature. When full, there is minimal air space inside the tank. The outside of the tank does have condensation though.

 

[Doc Stressor]

There are a couple of factors. As Skunkboat said, the fuel acts as a temperature buffer since it has a much higher volume and heat capacity than aluminum. So the daily temperature swings are minimized. Another factor is that a full tank greatly reduces the volume of air and thus water vapor in the tank. So the amount of water than can condense at the top of the tank is greatly reduced vs an empty tank. Finally, since the column of air is small, there is less exchange with outside air through the vent. The bulk flow of air through the vent is largely determined by the change in column of the air inside the tank. Air is forced out when the temperature is high and is drawn in when the temperature is low. With a little bit of air space, there is less change in volume than when you have a lot of air in the tank.