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Gas tanks full or empty or otherwise

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bobct

Advanced Contributor
"I just got my issue of BoatUS

"I just got my issue of BoatUS and it strongly recommends against leaving the tank at 1/4 or 1/2 full. They say either drain (not too practical or fill to 95%).

I read a million different opinions on this and decided to go the 1/4 full route with the reduced weight on the hull being the deciding factor.

250 gallons at 6lbs a gallon = 1,500lbs. At a 1/4 tank it's only 375 lbs. That's almost (6) 200 lb guys NOT standing on my boat all winter!

I overdosed on marine Sta-Bil and put at least an hour in the water to get it all mixed up. Some of my gas is new as well.

Not much I can do now. Has anyone else done the same in the northeast w/o a problem?

Should I plug up the vent hose?


Bob"
 
"I'm North of Lake Ontario

"I'm North of Lake Ontario. I fill both tanks, (100 gallons a side), and dump in the Stabil. The reason for filling is because in the Spring we get warm days interspersed with cool days and with 1/2 or 1/4 filled tanks that could lead to condensation and water in the tanks with the gas.

As well the stern of my boat is double blocked, has a fairly flat stern, and the two sets of blocking are right along the fuel tank lines.

I don't plug the vents, (chromed vents with wire mesh inside) because on a warm day in Spring I have actually seen some gas dripping out due to thermal expansion.

But ......that is just how I do it...and so far no problems"
 
"Don't plug the vent hose!

"Don't plug the vent hose! Fastest way to damage your tank. The vent will keep the pressure inside equal to that outside. With all that surface area, it doesn't take much pressure difference to put a lot of pressure on the tank.

Last year, Major_Tom posed a similar question regarding the condensation. Based on the mid-atlantic weather history, we don't get enough variation to generate a real condensation threat. I had an environmental engineer (actually thermo) go thru the calculations for a 250 gal tank half empty. Even using the extremes of temp, there isn't enough water in the air to cause more than a few ounces of water to condense out. Doing some 'dumb' things would change the variables and could increase that a lot. Keeping the hatches closed will help a lot as will ensuring adequate ventilation.

I've done the full, 1/4 full, and almost empty tank storage setups and not had any issues. Treat the fuel and then run the engine(s) long enough to get treated fuel to the carb. The stuff in the bowl will evaporate by spring."
 
"Bob,

In the few years I ha

"Bob,

In the few years I have had THIS boat as well as our others, I have never stored the boat with fuel. Prior to the ehtanol thing we ran the tank almost to empty to the point where I brought gas to the boat prior to launch in case we did not have enough to get to a fuel dock.

With the 34C I had MAYBE 30 gallons in it and a slightly higher shot of stabilizer. Its not that I would intentionally over do the stabilizer, It is just to hard to see those tiny lines for measuring or I squeeze the bottle too hard


In middle southern NJ, I've never had any problems even with temperature swings from the teens to the 50's. Great condensation weather"
 
"Most marinas--and their insur

"Most marinas--and their insurance companies--forbid storing a boat with 'empty' fuel tanks. Why? The volume of fumes in an 'empty' tank makes for a gigantic explosion.

Jeff

PS: It's hard to get boat tanks truly empty, as many have discovered while trying to rid them of contaminated fuel."
 
"Jeff, When I was a kid, we us

"Jeff, When I was a kid, we used gas as a bug and tar remover, charcoal starter, cleaner, paint remover and a few other dumb ideas. It just seems to be so much less "explosive" today. If you tossed a match onto a gas soaked log....POW

A few months ago I spilled about 2 oz on the dirt driveway by my garage. I figured I would burn it off rather and dig down and scoop out the soil. Tried to light it for a quick burn..nothing

NO..I am not a firebug"
 
"I'm more concerned with h

"I'm more concerned with having 300 gallons of gas go bad than a little water in the tanks. Water seps. remove the water but nothing I know of except writing a large check will get rid of bad gas, not to mention the other problems it may cause. Stabilzer can and should be used but for me filling up with fresh gas in the spring makes more sense. As Jeff mentioned, some marinas insist on full tanks to reduce the risk and hazards of exploding vapors, but my marina does not enforce this rule."
 
"couple questions here,is ther

"couple questions here,is there any coast gaurd or otherwise rule about empty tanks? what do you have to do to make a tank fume safe after its emptied? i plan on only using 1 tank next year. got an 84 34c silverton.i drained both tanks because of old fuel (5yrs sitting).starboard tank has what i believe to be a slight weep at a seam so i figured i'd leave it empty.tooo expensive to take it out.i only run around in the bay so fuel capacity is not an issue. if that empty tank is allowed to completely dry out is it fume safe??"
 
"Rick:

The only regs i'

"Rick:

The only regs i'm aware of state the tank (fuel system) needs to be "tight" and not leak. If the tank is empty and dry, it should be ok.

If you have one that is leaking, I'd empty it and then disconnect or isolate it to ensure you can't refill it if you don't want to remove it. The trick will be to empty it.

As noted above, some marinas have concerns about storage with empty tanks.

I'd leak the vent line on to ensure it still breathes."
 
i got it empty to a 1/2 gallon

i got it empty to a 1/2 gallon or less. left the fill cap off and the vent is still connected. thought about taking out the pickup tube fitting and running the air compressor hose at only a pound or 2 into it to circulate air out and dry it out. what do you think? the boats on blocks with no batteries or ignition source.
 
"Rick,
I would add that if th

"Rick,
I would add that if the tank is "bone-dry" there would be no problems running with an empty tank, other than the boats trim..(one side fuel the other not).

As Mark stated, the trick will be to get the tank completely dry. Remove all the fuel, as best you can, then vent the tank, (fill cap off) for a day or two, so that the fumes dissipate. If there is any residual weeping then you have a problem as that would create fumes in the boat.

Once the tank is, what you feel is completely dry, ensure it can NOT be fueled, (paint the fuel cap RED) but do not block off the vent line as that will help dissipate any possible leftover fumes.

PS>>>>>>>>I actually saw a fellow shove the hose of a small shop-vac,(hose connected on the "blow" side..not 'suck' into the gas fill and by using the exhaust air from the shop-vac blow out all fumes. After about 3 hours his tank was bone dry....worked for him
wink.gif
"
 
Be carefull playing with shop

Be carefull playing with shop vac's and fuel tanks. We had a guy at work decide to "vent" his bike tank. He accidently put it on the suction side. Twernt pretty.
 
I was wondering about that whe

I was wondering about that when I read it... My shop vac has occasional sparks from the brushes of the motor that you can see thru the plastic vent holes....Ka-boom?
 
"That should work....just be m

"That should work....just be mindful where the compressor is sitting. Under the vent fitting on a windless day would be real ugly, too."
 
Very definatly Ka-Boom! The co

Very definatly Ka-Boom! The compresser sounds like a great way to do it. Get a long hose and do the tank outside.
On another note I was taking to a guy that stores his boat at the same yard as a friend of mine. He is in the process of pulling his cusader out due to damage from E-10 fuel. The boat had fiberglass tanks and the rest as they say was history. He only had 100 hours on the engine. He said that crusader was going to fix it but said he trying to decide to stay with gas or to swap over to diesel.
 
"Guys ..

Perhaps I wasn&#39

"Guys ..

Perhaps I wasn't too clear. The guy who used the Shop-Vac used the regular hose but had a piece of garden hose attached to the hose and pushed it into the tank.

The Vac was a good thirty feet away from the fuel tank inlet, boat was on blocks, (Vac on the ground), and the blown air was going out the small vent as well as the fill inlet.

In my opinion there was no chance of a "KA-Boom...besides............he didn't have an air compressor...
wink.gif
and like most boaters, probably too cheap to go buy/rent one
lol.gif
"
 
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