Fuel-filler grounding on 22 Cruiser

[Sunbeam]

Hi folks,

In the thread I have going for my upgrade projects, the subject of grounding metal fuel fills came up. Although I have a call in to ABYC to clarify, it is definitely looking like the (original) metal fuel fills on my 22 Cruiser should be grounded. (I removed them earlier this year and found no evidence that they were ever grounded. There was nothing attached to them but the fill hose.)

I understand from reading how to attach the grounding wire to the fuel fill, but I'm not sure where to attach the other end (electrical is not my strong suit). My boat is not bonded, but (of course) it does have two negative battery terminals. There is also a negative bus bar. I also have a shunt (for battery monitor) although I'm thinking grounding is not a load so that shouldn't matter (?). Or maybe there is some other/better place to ground them.

Also if anyone already knows the appropriate wire size, that would be great. I see the resistance figure it has to be above, so I guess I could calculate it - but since this has probably been done hundreds of times on other 22's, maybe someone already knows?

Thanks,
Sunbeam

PS: Here is the relevant passage from ABYC's H-24
24.15 FUEL SYSTEM GROUNDING
Each metal or metallic plated component of the fuel fill system and fuel tank, which is in contact with the fuel, must be grounded so that its resistance to the boat's ground is less than one ohm. Wire ends shall not be clamped between the fill pipes and hose.

PPS: This discussion started as a tangent in another thread (that was not specifically about fuel fills). It's here in case anyone wants to read it:

http://www.c-brats.com/viewtopic.php?p=232878#232878

[Emurph8]

Before I removed my metal fills and old tanks there was a white wire attached to a bolt on the fill, it went front there to the fuel selector switch and then terminated at the bolt that went through the hull and mounted the outboard. So essentially it was grounded to the motor and the water? I intended to install new all plastic fill/vent combo which would not need to be grounded. But since receiving these have decided not to use them and am putting back the stock metal fills.

[Sunbeam]

[Bill K]

Please remember that some of the wire colors have been changed for boats.

My bonding wires are white. 1981 non C-Dory


I would have to go up to the boat and look, but am pretty sure the bonding wires are connected to a mounted anode on the bottom of the boat with a through bolt that the bonding wiring is connected too.

Bill Kelleher

[Sunbeam]

[Bill K]

You are out of my area of knowledge as I have a big boat now and have never had a trailered (sp) boat.

I am having to downsize am am very serious about C-Dorys.

Bill Kelleher

[Sunbeam]

[quote="Bill K"]You are out of my area of knowledge as I have a big boat now and have never had a trailered (sp) boat.
[quote]

Well thanks for your input, and if you decide on a C-Dory then happy shopping

It seems as though many of the diagrams "count on" the fact of one having an electrical fuel sender, which I don't have. Hopefully either someone here who is "in the know" will chime in, or else I'll get a call back from ABYC (or both!).

Sunbeam

[Emurph8]

My original setup, which I'm pretty sure was factory, did have fuel sending units in the grounding set up. And yours did not have sending units or grounding wires. So maybe they are not needed? I'm anxious to find out. I sure don't want to make a mistake on this job.

[thataway]

Generally "grounding" is between the fuel fill, metal fuel tank, and in some cases the fuel hose. In many C Dorys the tanks are plastic, and thus cannot be directly grounded--but the fuel gauge, if installed may be. The proper place for termination of the "ground" in this case--more of a bonding wire tie in, would be the engine bolts. A few boats do have either an anode plate, or proper ground plate, but not most C Dorys.

In either case, there is no real ground, unless you have a wire that you can connect to "earth" when you are pumping the gas on land. That would be ideal, but not done. Generally the bonding of the nozzle is adequate, as it touches the rim of the metallic fuel fill fitting.

Good practice is to touch the nozzle to the outside of the fuel fill fitting before inserting the nozzle, to dissipate any static electricity present in the system...Then insert the nozzle, and begin pumping fuel.

It is not ideal--but what we have to deal with.

[Bill K]

Now that I think about it when fueling a gas engine airplane there is a wire from the earth that is clamped to the airplane before starting to fuel.

Bill Kelleher

[Sunbeam]

I just got a call back from Brian at ABYC. Here's what I got from the conversation:

1) The boat being outboard or inboard powered is not really a distinction so much as it is that the boat has permanently installed fuel tanks with fills.

2) The metal fills need to be grounded.

3) Oftentimes, the fuel tanks are metal (or have senders) so the builder can simply run a wire from the fills to the tank (to ground the fills). Since my (our) tanks are plastic, this isn't an option. On the other hand, the plastic tanks also don't need to be grounded; it's just the metal fills that need to be.

4) The engine may be used for grounding, but really it all comes back to the negative in the electrical system (which the engine is attached to).

5) I said "So okay, I can use 12 gauge, stranded, green wire, and run it from each of my fuel fills to my negative bus?" He said yes, and reminded me that after setting it up I can check the resistance, which should be less than 1 ohm (of course what I'll do is "test wire" it and check the resistance before finalizing it).

I hope this helps and that I didn't misquote anything; I just got off the phone with Brian so hopefully it's all still clear in my head.

Sunbeam

PS: Interesting that - from all evidence I can find - C-Dory did not ground the fills when my boat was built. Do others with 22 Cruisers have grounded (metal) fills? (I'll be grounding mine when I reinstall them.)

[Emurph8]

Thanks for the research! That's what I will be doing also

[potter water]

Basic physics of this whole issue needs to be kept in mind. At least the way I view it. (I'm no brain surgeon, but I am a rocket scientist).

If the nozzle of the fuel hose is at a different electrostatic potential than the fuel fill area, be it metal or otherwise, then there will be a discharge between the two causing a spark. The reality is that the gas station and its pumps and its hoses and nozzles will likely be at a different electrostatic potential than your boat whether it is on a trailer or in the water. If the fueling station is on the water, and the pump nozzle system is grounded in the water and your fuel filler is grounded to any metal that is in the water, then it is likely that your electrostatic potential will be equal and there will be no discharge when the nozzle hits the filler opening.

On dry land with the boat on a trailer, then unless you clamp a ground from the pump and nozzle system to the metal of your filler, then there will likely be a significant difference in electrostatic potential. The boat and the trailer and the pump system are two different static systems and unless you physically connect them, there will be a difference in potential.

In the airplane world, that difference is taken care of by the fueling system having a separate grounding line and clamp that is clamped onto the airplane engine before the fueling nozzle is brought to bear on the fueling port.

I think that boat fueling would be safest if that was the case. But, you won't find such separate grounding connections in typical automotive or marine fuel operations. A poster above indicated that he grounds the station nozzle to the metal filler before inserting the nozzle. That is to me the only useful way to deal with the whole grounding issue. If the nozzle and the fuel filler is at the same electrostatic potential, then there is simply no issue of concern.

All that said, I have wire grounded my fillers to the engine/electrical system ground on the boat as a belt and suspenders solution.

Good luck with the mumbo jumbo of the various certification and standards organizations.

[Sunbeam]

It sounds like you really have a good understanding of the issue and lots of practical experience.

I'm not worried about the "mumbo jumbo" (I doubt anyone will be checking my boat for compliance), as much as I want to have things as safe as reasonably possible for myself and those around me. To that end, I sought info.

From what the ABYC fellow told me (and they are all about guidelines, not "laws from on high" - I find them to be reasonable and helpful), what happens when you fill the tank is that fuel swirls around, and that this combined with the plastic tank can cause static electricity, which can make a spark, which can ignite the gasoline vapors. From what I understand, grounding the fills dissipates the static and thus mitigates the hazard.

I guess not having the fills grounded doesn't mean sure explosion, because my boat had 50 hours on it when I bought it, so I imagine it had been filled through the ungrounded fillers; but it does sound like grounding them is the way to go, and it doesn't seem very difficult, so I believe I will.

Sunbeam

[potter water]

All I can say is that hundreds of CD's are out there with plastic tanks that the gas splashes around in and I'm not aware of any of them blowing up grounded or un-grounded. So, I'd add the wires if for no other reason than a picky insurance company finding an excuse not to pay up on a boat fire without regard to the reason for the fire. I'd never trust a wire that is installed out of sight and out of mine (And possibly broken at one end of the other), to save me from any kind of fire. I think there are probably laboratory controlled experiments or a few unusual situations that prove the theory of possible static discharge causing grief, but in practical terms, ground the nozzles against the fill port before inserting into the port and you should be good to go.