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ContinuousWave: Small Boat Electrical
Grounding Fuel Tank
|Author||Topic: Grounding Fuel Tank|
posted 04-29-2009 06:00 PM ET (US)
What is the best way to ground the fuel tank? I installed a new aluminum 40-gallon built-in fuel tank in a Boston Whaler REVENGE 19. [The boat] has trim tabs. Is running the ground wire from the tank to one of the mounting screws on the tabs a good idea? Does the tank have to be grounded below the water line?
posted 04-29-2009 07:50 PM ET (US)
All metallic components of the fuel system should be bonded together with a 10-AWG wire with green insulation. The fuel system ground should be connected to either the vessel ground plate on the hull or, if the vessel does not have a grounding plate on the hull, to the battery negative terminal. It is assumed the battery negative terminal is bonded to the chassis of the outboard motor.
On older Boston Whaler boats, and commonly seen as recently as in a 1990 Boston Whaler boat, there typically is a bronze metal circular fitting about 2-inches in diameter affixed to the transom below the waterline. This is the vessel grounding plate. To this plate the fuel system is bonded.
If the boat does not have such a grounding plate you can bond the metallic components of the fuel system to the battery negative terminal.
posted 04-29-2009 07:53 PM ET (US)
I would not use the trim tab as a grounding plate.
My understanding of the purpose of bonding the metallic components of the fuel system together is to keep them all at the same potential. Connecting the fuel system to the vessel ground plate will keep the potential at at the potential of the sea, which should be the same as ground potential.
posted 04-30-2009 07:59 AM ET (US)
Thank you jim. I understand
posted 04-30-2009 08:21 AM ET (US)
On boats without a grounding plate, the chassis of the outboard motor is considered the ground to the sea. Usually the outboard motor will have some bare metal anodes in contact with the sea. Even if the motor is tilted up, usually there are anodes on the mounting bracket that are still in contact with the sea.
posted 06-29-2009 06:10 PM ET (US)
Can you suggest where on the hull bottom that grounding plate is located on a 1979-80 22' Revenge? Mine was bottom painted by previous owner and I'm not seeing one.
If one does not exist, is there any advantage to adding one, (esp in terms of noise on the electronics) or will a ground through the battery and outboard be sufficient.
posted 06-29-2009 06:47 PM ET (US)
Dave, try the stern, port side, the wire travels through the splash well.
1983 Revenge 22
posted 06-29-2009 08:10 PM ET (US)
The location of the circular bronze grounding plate as mounted on the transom of a classic Boston Whaler hull, with 10-AWG green insulated wire attached, wire running through transom and protected with clam shell vent cover, is shown in
posted 06-30-2009 09:58 AM ET (US)
John, our hulls must be similar--the wire does run through the port side of the splash well. I'll get the paint off the plate today.
Now can one of you track that wire back for me? I need to connect a piece of electronics to "a dedicated earthling plate (e.g. dynaplate) in contact with the water." I'm not seeing a terminal under the dash with that green wire, nor do I see it under the front deck access port.
Thank you gentlemen.
posted 06-30-2009 05:09 PM ET (US)
If I remember correctly, it goes to the forward part of the fuel tank, and then to the plate the fill hose is attached to in the gunnel.
Like this, a couple of pictures down shows it.
posted 07-01-2009 08:01 AM ET (US)
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