Gas before or after storage

[Punchline Cap]

This topic comes up every fall
I think that the location of the vessel, specifically the local weather is a big factor. I am in the NYC area where normally winters are cold and humidity is low. The sun is low in the sky and that also reduces heating of boats. I have stored my boats for 15 years with usually empty tanks. Stabil - yes but only during the winter. Have I had any water in the gas issues? Nope.
The problem with the discussion is that for everyone who says they fill their tank, there is another who says they don't.
If I had my boat in Florida or a similar climate, I might approach things differently but here in NY, all options seem to be fine.
I feel that I would rather store with as little gas as practical because should anything go south like a water intrusion problem caused by perhaps a defective o-ring, I would put as little gas at risk as opposed to contaminating 100 gallons of fuel at $4 plus a gallon .

I am curious why a boat yard would require 3/4 full tanks for storage though unless it because they sell the gas

My boat yard is off shore. They come to my marina, pick up the boat, load it onto their trailer at the public ramp, do the fall maintenance and shrink wrap it. They do not sell fuel. On their service contract they require the boat has at least 3/4 tank of fuel when they pick it up. They put the fuel stabilizer in.

 

[seasick]

Unlike just about all boats except the latest model years have open air vented gas tanks. Tanks in autos and newer boats are 'closed' and have vapor recovery systems. In the case of 'sealed' gas tanks, the outside air does not get 'pumped' in and out as the ambient temps and more importantly the temp differences between the tank ambient air changes. Note that the condensation argument is valid for ethanol as well as non-ethanol gas. To a small extent, ethanol gas is better for small amounts or moisture since it will absorb about 1/2% water by volume. For non ethanol gas, that water just settles to the bottom. Of course with a lot of water, at some point ethanol gas will experience phase separation which is a lot worse than just excess water mixed in non ethanol gas.
My earlier question about what the goal is in filling or not filling the tank relates to the topic of tank corrosion from water. Depending on the temp swings and the relative humidity, a tank can sweat on the inside and/or the outside. If you store your boat in a location where it gets cool at night and but the days are warm and there is some humidity, the ambient air under the deck will be warmer as the outside temps increase for quite some time before the tank of gas catches up, if it evers does.
The warm air on the cooler tank outside surfaces will result in condensation. Your tank will be wet on its outside.
Likewise if the tank eventually warms up to the daytime temp, at night it may very well condense on the inside.
So the effectiveness or need to store full, empty or somewhere in between will vary for folks in Florida as opposed to those in a desert locale.

At my boat club there are about 100+ boats and over the years, very few condensation issues . There are those who worry about bad gas for various reasons, such as extended storage times (multiple seasons), suspicion of water intrusion ( gee, why is there no o-ring) etc. Those folks are much more likely to dump the gas. At the same time, there are a lot of folks who are more than willing to take their gas.
The exchange goes like this " How do I get rid of may gas". The response often is " Put it in my tank".

 

[Punchline Cap]

After retiring from my trade after 40 years I got a part time job at a lawnmower store doing deliveries and pickups. The majority of bad fuel issues seemed to be with snowblowers. It seems that the heat of summer has more effect on ethanol added fuels than the cold of winter. We would instruct every snowblower customer to always put Stabil in the gas and or run the tank dry in the spring.

 

[DennisG01]

It seems that the heat of summer has more effect on ethanol added fuels than the cold of winter.

This is explained by simple science. Warm air holds more moisture.

 

[SkunkBoat]

I have done both. I'm in the near empty camp now that I can hold 250 gals.

If you are going the filled route do not FILL it. I did that on a 60 gal tank. Filled in November..come April.. 85 degree day ...it expanded out the vent.

 

[seasick]

I have done both. I'm in the near empty camp now that I can hold 250 gals.

If you are going the filled route do not FILL it. I did that on a 60 gal tank. Filled in November..come April.. 85 degree day ...it expanded out the vent.

 

[Dear Prudence 2.0]

I am in the fill and stabilize camp for winter storage. I use Stabil on most fill ups during the season as well. I have always filled and stabilized fuel in motorcycles, cars not used during the winter, lawn mowers, chain saws, etc. I’ve never had to dump and replace the fuel in the spring. We live in Maine. We lived in Kansas for twenty years and followed the same routine..

 

[rprieser]

Any environment will cause condensation to form inside your fuel tanks over time and that's bad. Don't believe me, do this little experiment: Leave a half full container of mustard in your refrigerator for about a month, then turn it over and notice what first squirts out -- Its water from condensation forming inside the mustard continer and the same thing happens inside your fuel tanks only on a much larger scale. It's physics and condensation will happen. You should fill or at least 7/8 fill fuel in your tanks. ESPECIALLY if you are using regular pump fuel with ethnol.

 

[SkunkBoat]

Any environment will cause condensation to form inside your fuel tanks over time and that's bad. Don't believe me, do this little experiment: Leave a half full container of mustard in your refrigerator for about a month, then turn it over and notice what first squirts out -- Its water from condensation forming inside the mustard continer and the same thing happens inside your fuel tanks only on a much larger scale. It's physics and condensation will happen. You should fill or at least 7/8 fill fuel in your tanks. ESPECIALLY if you are using regular pump fuel with ethnol.

Not a good analogy....the water in the closed mustard container was already in the mustard.

 

[seasick]

Not a good analogy....the water in the closed mustard container was already in the mustard.

So that is why my yami wont run on mustard!

 

[Throttle1971]

Thanks for all of the responses. I went with half tank of gas and stabilizer. Boat will be pulled and dunked in April.

 

[grady33]

I have an Express 330 and fill both tanks and add stabil before fill up. Been doing that for more than 20 years with this boat and my 272 and never had a problem. I only use non-ethanol fuel!