filling portable fuel tank while tank on top of boat? - The Hull Truth

Hooked Up · 05-09-2006, 01:13 AM

Hello guys. I just bought a 27 gallon "above deck" fuel tank. I rather fill the gas tank on top of the boat, since it gets pretty heavy to lift it over the gunnels. I am thinking of buying some SS cable and tying it at the tank so that I can make that cable contact the ground (surface) while Im filling it at the gas station. If anyone has any better ideas on how to best do this safely, Im all ears. I figure I need to find a way to ground the tank temporarily while filling it up. THanks to all in advance.

t3rockhall · 05-09-2006, 07:41 AM

It depends.
Read this article:

http://www.uscgboating.org/alerts/alertsview.aspx?id=27

baypro21 · 05-09-2006, 07:56 AM

I'm not sure if it's necessary to have that ground strap. The pump nozzle is grounded thru the hose (metal braid just under rubber skin of hose). Might be a good idea to ground the new tank to your existing, built in tank. Cars and boats on trailers don't have ground straps hanging down contacting the earth. All you have to do to disipate any differance in potential would be grab the metal part of the nozzle and touch the fuel inlet with your other hand. The high resistance of your body should not let it spark but still get rid of any differance in potential. This procedure is recommended when filling the car on dry days.

Hooked Up · 05-09-2006, 08:59 AM

Why is filling a plastic portable tank inside the boat different than filling a portable tank in the bed of a pickup truck? I thought there could be a static discharge since the tank is not grounded. On the link, it says "It is recommended by ABYC and the USCG that new installations of this type of fuel fill assembly DO NOT INCLUDE any attachment to the boats bonding system." That may be for permanent plastic tanks>!>!???

rogerstg · 05-09-2006, 09:07 AM

Quote:

Hooked Up - 5/9/2006 1:13 AM

I figure I need to find a way to ground the tank temporarily while filling it up.

That makes no sense to me. After all, you don't run a cable to an earth ground when filling your truck or your car do you? Same with a boat. Neither are "gounded to earth" due to the insulation properties of the tires.

rwidman · 05-09-2006, 10:00 AM

Quote:

Why is filling a plastic portable tank inside the boat different than filling a portable tank in the bed of a pickup truck?

It's not and you're not supposed to do that either!

Kamper · 05-09-2006, 11:07 AM

Some states require portable tanks to be removed from a boat prior to filling. IMO, that's a joke for anything larger than 6-12 gallons. Just in case, install the tank in a manner that looks permanent.

As for the static thing... Probably wont hurt anything to ground it. Keep the nozzle in touch with the tank neck so any static charge that builds up is equalised without a spark. There's probably a more technical word for it but I'm sure you know what I mean.

Where on the boat will this thing be mounted? If you set it somehwere hazardous the water cops may send you home early.

jethro1 · 05-09-2006, 03:20 PM

The fuel tank of a car/truck does not normally need to be bonded to earth because it is bonded to the frame of the car/truck. This dissipates any static electricity that might build up and cause a spark between the inlet of the tank and the nozzle.

Any portable type tank that is sitting in the bed of a truck or a boat does not have a good way to dissipate static electricity buildup. In some cases the build up of static electricity reaches sufficient voltage to jump from the tank to the nozzle. This, of course, is a source of ignition for the fuel vapors coming out of the tank as it is being filled. The spark jumps from the tank to the nozzle because the nozzle is bonded to earth via the hose and the spark is seeking the easiest way to get to a ground point.

Hooked Up, it is a great idea to fabricate and use a bonding wire from the tank to a source of ground. Hook it up before you do anything and remove it after all fueling is over. When a fueling truck is fueling an airplane they go to great extremes to eliminate the build up of static electricity. The airplane is bonded to earth via one cable, the fuel truck is bonded to earth via another cable and the airplane and the truck are bonded to each other via a third cable.

SeaJay · 05-09-2006, 03:30 PM

Just remember, if it ignites accidently, kabluey!!!

rwidman · 05-09-2006, 03:58 PM

Quote:

Kamper - 5/9/2006 9:07 AM

Some states require portable tanks to be removed from a boat prior to filling. IMO, that's a joke for anything larger than 6-12 gallons. Just in case, install the tank in a manner that looks permanent.

If you install a tank permanently or use one larger than 6 gallons, your boat is subject to some additional regulations regarding fire extinguishers, etc.

ndb8fxe · 05-09-2006, 05:44 PM

I recommend touching the nozzle to the outside of the tank (not near the fill port) before fueling. I do this with all my portable tanks even though I put them on the ground before fueling. This will disipate any built up charge. After, as said before, keep the nozzle in contact with the filler neck throughout the fueling process. This in essence will bond the fuel tank with the nozzle.

I never see aircraft fuelers ground airplanes anymore(not saying no one does it) and in fact NATA(National Air Transportation Association) no longer recommeds the procedure however bonding the fuel truck with the airplane is imperitive. Due to the large surface areas of aircraft wing paired with flowing air makes aircraft more suseptible to static buildup.

I would be extra carefull when fuelling in cool/cold dry air. This is the same situation when you usually get a static discharge when touching a car. Moist or humid air makes a static discharge less probible.

Hooked Up · 05-09-2006, 06:32 PM

I was thinking that the easiest way to do this was to wrap a cable round the filler neck and have that cable touch the ground while I was filling it. I figure I do that + touch the outside of the tank with the nozzle + keep the nozzle in contact at all times. This all sounds better than lifting the 180 lb tank over the gunnel.

There has to be a way of positively eliminating the risk of static while doing this. The tank I bought is a Tempo 27 gallon above deck tank. Its designed for boats of course and therefore approved to be carried on board. I do not intend to permanently installed the tank on the boat. That will make it illegal, as it is not a permanent tank. Hell you could get your boat confiscated (by my agency) for carrying illegaly installed tanks, so don't want to do that. In any case, if anyone has any more ideas on how to do this safely, thats what I like to hear. Thanks to all for the inputs.

warthog5 · 05-09-2006, 07:12 PM

A little while back there was a guy filling regular plastic gas can's in the back of his truck. You guessed it. Static electricity got it.

Blew the guy back and burned him. Not life threatning, but his truck was a total loss.

jobowker · 05-09-2006, 11:59 PM

All this talk about grounding would be all well and good except for one small problem - the tanks are plastic.
Don't fill a plastic tank while it's sitting in a truck with a plastic bedliner. No manner of straps or wires will help you period. You need to not be a lazy ass and take the tank out of your truck, fill it while it's on the ground, and then lift it back in. The same holds true for a plastic tank sitting on a plastic (FRP) boat. If it's too heavy to lift, either eat your wheaties & start working out, switch to a metal tank, or buy a smaller tank. This isn't something to fool with. If the tank was metal, then the grounding strap would dissipate the charge.

In case it wasn't clear, there is NO way to properly ground a plastic tank sitting on a plastic bedliner or on a fiberglass boat deck unless you can somehow convince plastic to start conducting electricity similar to the way steel can. This will involve some alchemy and rearranging of the periodic table, which is well beyond the scope of this discussion.

Tomcod 5 · 05-10-2006, 12:06 AM

static electricity builds up in plastic fuel tanks. Not sure of the physics, but many vehicles (our work vans for one) have a ground strap that drags the ground under the vehicle.

76GMC1500 · 05-10-2006, 03:14 AM

I have seen first hand a static discharge from an ungrounded hose that had oil moving through it. The hose was being used to suck oil out of a generator sump and into a filter buggy. The sump was metal and grounded to the hull of the ship. But, the hose is plastic and does not conduct electricity so the charge built up in the hose. When an engineer went to pull the hose out so he could look in the sump, ZAP! It lit his whole arm up blue and made quite a bang. I could hear it quite clearly while I was standing next to the other, running generator.