Grounding for VHF

[MADRIGAL]

I am replacing the fixed-mount VHF radio on my small sailboat, and I see that the new radio has a grounding wire in addition to the positive and negative DC leads. The old one had only positive and negative leads. I take the battery out of the boat to charge it once or twice in a season, but otherwise it is kept fully charged by a solar panel. The only draw is the VHF/GPS unit and navigation lights. My question is, what do I do with the ground wire? Do I need an under water bronze grounding plate? Thanks in advance; I know there are forum members with plenty of experience with radios and electrics.

 

[VicS]

My VHF is not grounded

What does the manual/ installation instructions for your new radio say about grounding ?

What is your new radio ?

I found this statement in the instructions for a Furuno VHF.

"While special grounding is not generally required for VHF radiotelephones, it is a good practice to properly ground all electronic equipment to the ship’s ground system",​

but I guess you do mot have a ground system

​

 

[MADRIGAL]

The radio is an Icom M330G. The instruction manual shows the ground and gives the description, “Connects to a vessel ground to prevent electrical shocks and interference from other equipment occurring.”

 

[VicS]

I see it only has a ground terminal. ... Ignore it

 

[MADRIGAL]

Cheers. That was my plan, but it doesn’t hurt to seek greater wisdom

 

[differentroads]

Yep, 'grounding' is not needed on our types of VHF installation where the negative wire is almost always also the boat's 'ground' - connected to the sea through the hull anode.

Some installations might have isolated grounding and negative supply and that is what the seperate ground connection is for - connecting the metal case to the boat's grounding system to screen the radio from radio frequency interference. We can put a connection in from the grounding screw to the boat's negative circuit but my limited experience is that its not very effective. It didn't stop the RFI on my VHF from a nearby LED light anyway.

 

[VicS]

Yep, 'grounding' is not needed on our types of VHF installation where the negative wire is almost always also the boat's 'ground' - connected to the sea through the hull anode.

Some installations might have isolated grounding and negative supply and that is what the seperate ground connection is for - connecting the metal case to the boat's grounding system to screen the radio from radio frequency interference. We can put a connection in from the grounding screw to the boat's negative circuit but my limited experience is that its not very effective. It didn't stop the RFI on my VHF from a nearby LED light anyway.

MY VHF does not have a Ground terminal and there is no mention in the instructions that there should be any connection between the DC negative and the water.

There is no anode and the only connection to the water will be via the outboard when that is lowered.

There is no connection between the case and the negative either

 

[Skylark]

The radio is an Icom M330G. The instruction manual shows the ground and gives the description, “Connects to a vessel ground to prevent electrical shocks and interference from other equipment occurring.”

............so why chose to ignore it?

 

[Tranona]

Yep, 'grounding' is not needed on our types of VHF installation where the negative wire is almost always also the boat's 'ground' - connected to the sea through the hull anode.

It is only recently that it has been a requirement to ground through an anode. The majority of older boats either do not have anodes at all, or have anodes to protect specific items such as saildrives or propellers that are not used as electrical grounds, nor would provide a ground via the negative of the DC system.

 

[PaulRainbow]

MY VHF does not have a Ground terminal and there is no mention in the instructions that there should be any connection between the DC negative and the water.

There is no anode and the only connection to the water will be via the outboard when that is lowered.

There is no connection between the case and the negative either

The "ground" connection on marine electronics is not there for "grounding" in the same sense as you ground/Earth your AC systems. It is a bonding/drain wire, designed to prevent build of of static and help to stop electronic interference.

It should be connected to, in order of preference:

The ground plane or grounding cable.
The engine block (if inboard).
The negative post of the battery.

Not all equipment has a ground/drain wire (Raymarine almost always does).

 

[PaulRainbow]

It is only recently that it has been a requirement to ground through an anode. The majority of older boats either do not have anodes at all, or have anodes to protect specific items such as saildrives or propellers that are not used as electrical grounds, nor would provide a ground via the negative of the DC system.

See post #10, it's not an electrical ground in the normal sense.

 

[MADRIGAL]

See post #10, it's not an electrical ground in the normal sense.

Thank you for the explanation. Is this what is meant by the RF ground? I have heard of its being run to the negative post of batteries before, but I could not think why that would help reduce interference. Clearly I don’t know much about radio.