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Author Topic:   Grounding an Aluminum Fuel tank
Feejer posted 01-03-2008 03:57 PM ET (US)   Profile for Feejer   Send Email to Feejer  
Anyone have any ideas on the proper way to ground an aluminum fuel tank on a 05 Montauk 170?


Bella con23 posted 01-03-2008 06:24 PM ET (US)     Profile for Bella con23  Send Email to Bella con23     
Boston Whaler uses a green stranded #10 conductor to bond from the tank to the negative side of the 12 volt connector bus. That would be adequate for safely discharging static from the tank during a fuel up.

If you plan on removing the tank, I would suggest a good quality push-in connector near the tank.

Bulldog posted 01-03-2008 06:25 PM ET (US)     Profile for Bulldog  Send Email to Bulldog     
Use the search function and type in "grounding tank" there is a lot of information on it there. I myself do not think your tank should be grounded electrically to battery negative, unless you are installing a electric fuel sender. My old Whaler has an internal tank that is bonded to the fuel fill, and also a ground plate in the water at the stern, but not grounded or tied to the battery negative terminal.....Jack
Feejer posted 01-03-2008 07:36 PM ET (US)     Profile for Feejer  Send Email to Feejer     
Thanks, The tank will not have any type of electric sender. I have sent an email to BW to get their view on it.
Bella con23 posted 01-03-2008 09:36 PM ET (US)     Profile for Bella con23  Send Email to Bella con23     
The idea of a "Bonding Conductor" is to isolate stray and/or fault currents from current carrying conductors. I couldn't agree with you more on that Jack. However, on this 1999 Conquest, BW decided it would be best if the ground plate was bolted to the outboard transom mount.

This direct connection to the outboard's negative side of the boats electrical system allows the manufacture to connect the bonding conductor to the closest negative termination.

Is this proper? Not in this electricians eyes, and obviously not yours either. If we were to have a shore powered non-isolated battery charger onboard, and the outboard lowered into the water, I think there would be problems keeping sacrificial zincs on the outboard and maybe worse.

I would be interested to hear Boston Whalers response to your inquiry Feejer.

Personally, If your talking about a deck mounted tank with an all aluminum fill neck and fill cap, I wouldn't bother.
The fuel nozzle is your static bond as long as your filling up.

Feejer posted 01-04-2008 07:42 AM ET (US)     Profile for Feejer  Send Email to Feejer     
I hope to hear from BW today. Some one THT had posted this.
Here's the regulation:

183.572 - Grounding

Each metallic component of the fuel fill system and fuel tank which is in contact with fuel must be statically grounded so that the resistance between the ground and each metallic component of the fuel fill system and fuel tank is less than 100 ohms.

However it does not say if this applies to outboards. I will being stopping by my local dealer Saturday morning to get their input also.

Feejer posted 01-04-2008 09:17 AM ET (US)     Profile for Feejer  Send Email to Feejer     
Here is the response from BW

"When Whaler grounds fuel tanks, it is grounded to the negative buss bar, which leads to the negative side of the battery which then leads to the engine as a ground."

However they did not say weather or not the tank must be grounded

Would I pull a grounding wire from the engine side thru the rigging tube to the RPS or from the buss side?

Bella con23 posted 01-04-2008 09:36 AM ET (US)     Profile for Bella con23  Send Email to Bella con23     
The concern of static buildup is primarily caused by the fuel running from the fuel inlet down though a rubber hose connector, and into the fuel tank.
With this arrangement, it would be necessary to follow the regulation you cited in the previous post.

Again, if your fuel tank is a one piece arrangement with no rubber hose connection between the fill and the tank itself, you would not have a potential for static buildup.

Remember, the fuel pump nozzle itself is designed to bleed off static before it has a chance build to any potential danger during a fill.

Feejer posted 01-04-2008 10:31 AM ET (US)     Profile for Feejer  Send Email to Feejer     
I just spoke with the manufacture who would be making the tank. All of their tanks are made with a small tab to attach a grounding cable to it. Now all I have to do is figure out how to run the cable from the bus bar to the tank.
Bulldog posted 01-05-2008 09:50 AM ET (US)     Profile for Bulldog  Send Email to Bulldog     
Sounds like you are leaning towards bonding the tank to the battery negative buss, which is what Whaler recommends for it's boats with internal tanks. I assume your tank is big enough that in reality it won't be really portable, so bond it as Whaler does. I don't think Whaler will ever say that you have to bond your tank as the small Whalers with portable tanks from the factory are always small tanks easily carried full, it's the aftermarket tanks of 24 to 28 gallons that sort of enter a gray area about if they are portable. There are regulations regarding venting overboard and such that would be impossible for you to meet. On my former Whaler which was a Newport with twin 9 gallon tanks when filling at a dock, I would always wait a bit and also wave a throw cushion a couple times in the rear of the boat to disperse gas fumes in the boat. When filling my Revenge at the dock or on the trailer my system is bonded from the transome ground plate to the grounded fuel pump nozzle which allows static buildup to bleed off to a true ground. I'm an electrician who knows that bond, ground and negative are three different things and maintain a fuel pumping station for a fleet of hospital trauma copters. I have seen a staic discharge fire at a pump and truly feel you will be fine either way, but most importantly when filling keep the fuel nozzle in direct contact with the filler neck.......Jack
A2J15Sport posted 01-15-2008 02:35 PM ET (US)     Profile for A2J15Sport  Send Email to A2J15Sport     
If you have the ability to gound the tank, do so. You have everything to lose if there ever should be a stray static spark.

I might be a bit gun shy (I was badly burned as a child from a gas filling acccident) but I carry a loop of wire with aligator clips on each end. I connect the clips to the portable fuel tanks (OMC six gal.-steel) and the other end to the filler nozzle before I put the nozzle in the tank.

I really should remove the tanks, from the boat, before filling but the ground wire does the same thing.

Some will say that the trailer is insulated from the "ground" anyway, by the trailer tires, so why do that? That is somewhat true. However, your tow vehicle fuel tank is grounded to the chassis for that very same reason and your vehicle is also sitting on rubber tires.

The key to avoiding static electricity discharges is to not give it a concentrated area in which to discharge. By grounding the tank(s) to a large area the static charge, if present, is spread out and diminishes.

Why risk it? It only takes one incident to effect a dramatic change in your life.

GreatBayNH posted 01-17-2008 08:22 PM ET (US)     Profile for GreatBayNH  Send Email to GreatBayNH     
Another argument for upgrading to twin 12 gallon tanks. I fill mine on the ground at the local gas station. If you want permanent fuel tanks buy a boat with an internal fuel tank.
Feejer posted 01-18-2008 07:51 AM ET (US)     Profile for Feejer  Send Email to Feejer     
Seth, I hope to be moving up to a new Dauntless or Outrage. Should know in a few weeks
GreatBayNH posted 01-19-2008 10:22 AM ET (US)     Profile for GreatBayNH  Send Email to GreatBayNH     
Awsome! I'm jealous. How did the swim ladder grab rail purchase go?


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