"Locking" Type Gas Cap?

[LuvBoating]

Have a 1992 Celebrity 200 Cuddy Cabin. Don't know just how many gallons the tank holds, but think the gauge showed 3/4 the last time we had the batteries hooked up (Nov 2014) and before had "winterization" done. Couldn't take the boat out last year due to a surgery. Was going to syphon some of the gas out, but apparently the tank is empty. Tried two different hoses in the tank, all the way until they stopped going in, brought out and no wetness/gas on the tube. Not sure if gas was stolen or evaporated. There is a key that is used to open/close the metal gas cap, but a screw driver could be used as well, to take the cap off. We've been looking at a Metal Locking Gas Cap on Amazon, but since our existing cap fits flush with the filler, appears the only way to put this metal one on, and tighten it up, is with the key that locks/unlocks it.........especially, if the locking one screws down flush to the filler. OTOH, the plastic Locking Gas Caps have a "turning" thing on the top as well as the lock in the middle.

If, the metal one fits flush to the filler, the only way to tighten/untighten it would be with the key. Don't think that would be a good idea.

We are going to hook the batteries back up to the boat and see what the gas gauge says and then put some gas in the boat. But, if indeed, someone did steal the gas, we want to put a "locking" type cap on it.

All thoughts/recommendations will be really appreciated. Thanks.

 

[GA_Boater]

Your siphon hose probably got snagged in a bend in the filler hose and isn't reaching the tank. Those hoses can have some extreme bends.

Was the gas treated? What do the fumes from the filler smell like - Gas or something else?

 

[alldodge]

Dad always told me, Locks keep honest people honest, a thief will tear things up to get to what they want. Now if someone else is nearby without a lock, they would go their first. House boats are the most stolen from in my neck of the woods, lots more gas in them and easier to get at

Agree with GA on the possibilities other then someone steeling it.

 

[LuvBoating]

Gas was treated and could smell gas at the Filler. BUT, when I shook the boat from side-to-side from the corner of the stern, wife and I couldn't hear any sound from gas tank.
Don't have to have the cap key to take it off, tapping a flat-head screw driver in one of the two key holes will turn the cap, so it would come off.

 

[LuvBoating]

So, could the gas have evaporated? From what we remember, there was at least 30 gallons in the tank in Nov. 2014.

 

[Bondo]

Ayuh,.... Ya might have better luck pullin' gas from the gas line at the motor,....

As noted, I doubt you can stuff a hose down the fill pipe, All the way to the bottom of the tank,....

 

[alldodge]

So, could the gas have evaporated? From what we remember, there was at least 30 gallons in the tank in Nov. 2014.

I don't think so, not 30 gallons

Maybe someone did steal it, and if so you could look on the bright side, you don't have much worry about pumping bad gas out.

Also check for a leak, like soft wood around the tank and broken fuel line.

 

[GA_Boater]

Locking caps and replacement keys for non-locking caps.

 

[LuvBoating]

Looks like we are going to hold off on getting a metal locking gas cap. Will know more about amount, if any, gas is in the tank once we hook up the batteries in the boat and check the gauge. If empty, will only partially fill the tank and then monitor it.

 

[roffey]

I once tried to stick a hose in the filler for my Wellcraft and as stated above it would not go. I had to go directly into the gas tank and bypass the filler hose.

 

[Old Ironmaker]

30 gallons of fuel does not evaporate,. Fill the tank and see what it takes to fill. Sad when someone needs to steal gas. It happens.

 

[Scott Danforth]

30 gallons of fuel will evaporate over time, however not over 1.5 years. more like about 3 to totally evaporate and turn to varnish in a vented tank (estimating some of the conditions).

the military even has a manual on it, and there are many technical papers http://www.dtic.mil/dtic/tr/fulltext/u2/769709.pdf; http://www.tandfonline.com/doi/pdf/10.1080/10473289.1994.10467294 ; https://www3.epa.gov/ttn/chief/ap42/ch07/final/c07s01.pdf

(mass loss rate)/(unit area) = (vapor pressure - ambient partial pressure)*sqrt( (molecular weight)/(2*pi*R*T) )

vapor pressure chart

WINTER WINTER SUMMER SUMMER AVIATION JET FUEL
GASOLINE GASOLIN GASOLIN GASOLIN GASOLINE & KEROSENE
TEMP REID REID REIDVP REID
�F 14-VP 12-VP 10-VP 8-VP

40 4.8 4 3.4 2.8 2.2 0.9
50 5.9 4.9 4.1 3.4 2.8 1
60 7.4 6 5 4.1 3.5 1
70 8.9 7.4 6 5 4.2 1.2
80 10.7 9 7.1 5.9 5.1 1.4
90 12.8 10.6 8.6 7 6.2 1.7
100 14 12 10 8 7.4 2

And,for stagnant conditions you have to take into account the change in local ambient partial pressures as it vaporizes, ie, near the surface you'll get a layer of high partial pressures which will slow the evaporization.

If you have any wind blowing (assuming boat stored outside) then I'd estimate it with a zero ambient or maybe 50% (ie, half the gas vapor pressure).

Long story short, expect a bit of evaporation in a vented system, more with higher temps, a bit of wind, etc. I would expect that you find about 15-18 gallons left of your original 30