How to prevent diesel theft by syphoning?

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sjnssn

sjnssn

Member
Joined
Jul 22, 2024
Messages
15
Location
Ladysmith, B.C.
Vessel Name
Qwinoa 2
Vessel Make
1977 34' CHB Trawler
I have a 1977 CHB with 2 1/4" inside diamiter diesel filler pipes. Have had thefts by syphoning. Unable to find locking fuel caps and not keen on that solution as the lock tumblers are on the deck and exposed to salt and dirt. Looking for way to prevent syphon tube going down the fillerpipe. Found Fuel Safe Anti-Siphon Device, #FUELSAFE, but it"s minimum diamiter is 2 1/2". Anyone have a creative idea?
 
How about stainless steel hardware cloth, say 1/4". Wad it into a ball and shove it down the filler hose as far as it will go with a dowel.
 
It appears that there might be something, purpose built to fit a Freightliner that may prove useful to you.


I for one would not want to stuff anything down my fuel fill hoses, too hard to get out.

If there is enough length in the filler pipes or hoses you may be able to install a ball valve below decks which should be secure if the hatch locks.
 
SIBERNUT said:
So switch the 2 caps. YOU would know which was fuel.
Click to expand...

At this point the thief and their friends also know which one is the fuel fill.

You may be inviting someone to put something in your fuel tank in retaliation.

Much smarter to keep them out.
 
The more important question is, "how far will they go to steal fuel?" Locks only keep the honest people honest.

My solution, if you can get to where the fill hose connects to the fuel tank, is to put a screen on the top of the tank pipe. Make it slightly smaller than the OD of the tank pipe, but larger than the ID. Then reinstall the fill hose.

Ted

Screenshot_20240723_163148_eBay.jpg
 
Last edited:
At $5/Gallon here in So Cal, I'm carrying about $1000 worth of fuel when full. Guess I gotta re-think this one!
 
Delta Riverat said:
How about stainless steel hardware cloth, say 1/4". Wad it into a ball and shove it down the filler hose as far as it will go with a dowel.
Click to expand...
I like that idea. Question what will stop SS cloth from falling into tank?
 
luna said:
It appears that there might be something, purpose built to fit a Freightliner that may prove useful to you.


I for one would not want to stuff anything down my fuel fill hoses, too hard to get out.

If there is enough length in the filler pipes or hoses you may be able to install a ball valve below decks which should be secure if the hatch locks.
Click to expand...
Concern is the truck part is Aluminum that will corrode over time.
Ball valves are something I'll have to concider!!
O C Diver said:
The more important question is, "how far will they go to steal fuel?" Locks only keep the honest people honest.

My solution, if you can get to where the fill hose connects to the fuel tank, is to put a screen on the top of the tank pipe. Make it slightly smaller than the OD of the tank pipe, but larger than the ID. Then reinstall the fill hose.

Ted

View attachment 156733
Click to expand...
Good idea but fill pipe is welded to the tank.
 
luna said:
At this point the thief and their friends also know which one is the fuel fill.

You may be inviting someone to put something in your fuel tank in retaliation.

Much smarter to keep them out.
Click to expand...
Agree!!
 
sjnssn said:
I like that idea. Question what will stop SS cloth from falling into tank?
Click to expand...
It's pretty tough stuff. If it's big enough to "not go gently" I wouldn't think it would fall. It'll be hard enough to push in and probably not make it past the first bend in the hose. On my boat the fill hoses are far from a straight shot to the tanks.
 
Fluffy?
 

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sjnssn said:
Concern is the truck part is Aluminum that will corrode over time.
Ball valves are something I'll have to concider!!

Good idea but fill pipe is welded to the tank.
Click to expand...

It's likely that your fuel tank is also Alum. The truck part, once stuffed into the filler opening and being regularly bathed in diesel fumes in a place where there should be no water will likely last as long as the tank.
My concern would be, should I want to, how do I get it out?

Ball (or gate) valves will be expensive to fit in the hose or the fill pipe if there is no hose. I would make provision to lock either of these 2 valve types.
A 2 1/2" globe valve on the other hand has such a contorted path for fuel passage that it probably could be left open and still stop the 1/2" diameter siphon hose.

Just in order to be aware, in what Marina (in Ladysmith?) is this occurring?
 
Man, our fuel tanks sit pretty low to the waterline and starting and maintaining a siphon would be difficult at best, unless you mean while on the hard. Too bad the thieves don't put all that effort and industriousness into something more productive...
 
luna said:
It's likely that your fuel tank is also Alum. The truck part, once stuffed into the filler opening and being regularly bathed in diesel fumes in a place where there should be no water will likely last as long as the tank.
My concern would be, should I want to, how do I get it out?

Ball (or gate) valves will be expensive to fit in the hose or the fill pipe if there is no hose. I would make provision to lock either of these 2 valve types.
A 2 1/2" globe valve on the other hand has such a contorted path for fuel passage that it probably could be left open and still stop the 1/2" diameter siphon hose.

Just in order to be aware, in what Marina (in Ladysmith?) is this occurring?
Click to expand...
Good Points
The new Oyster Bay Marina beside 'Dog Patch"
I'll check out the filler tube design in detail and get back to you all
 
We met the owner of a boat who had several hundred gallons removed from his tank(s). He put a ball valve between the deck fill and the tank. He does have good below deck access. I asked about forgetting to open the valve before filling. He said it’s something he won’t forget. Everytime time he fills up, it’s a painful reminder of losing ~$1,500 worth of fuel.
 
If there is room for a valve then that would be the way to go. I don’t like the idea of stuffing something down the filler hose. If it impedes fuel flow into the tank it could end up being a PITA getting it out. You could turn a half hour fill up into hours due to slow flow rate.
 
The idea of fuel being stolen from my boat has never crossed my mind until now. Now that I think about it, my boat happens to have a 12-in length of hose between the filler neck and the deck fitting.I suppose if I were to have this problem, it would be easy for me to install a set of ball valves in the filler hose that I could shut off from inside the boat. Fortunately for me, I am able to reach the filler necks from within my engine compartment quite easily. Not sure about other people's boats, but for me this is something that can be done. Now that I think about it, I actually see that you can order electrically operated ball valves that can be opened or closed with the push of a button. That might be a better option.
 
A globe valve with it’s Z shaped fluid path surely would stop the siphon hose from reaching the tank even if it is left wide open.
You would, in normal operation never need to operate the valve.
Don’t overthink this.
 
Similarly, a large check valve should let fluid in and not a hose.. if they could snake the hose in it would likely become yours! :D
 
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