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brokesailor 08-13-2011 08:53 AM

Grounding strips
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My boat has this network of copper strips, attached to seacocks etc. What is this associated with? Looking at the grounding plates from the inside of the boat there is nothing hook up to them. The mast ground wire (?) is attached to one of the keel bolts.

fairbank56 08-13-2011 10:31 AM

RF ground for an HF SSB radio antenna system.


mitiempo 08-13-2011 02:08 PM

Or bonding for protection from electrolysis. Most recommend against bonding now but it was very common in the past.

bandaidmd 08-13-2011 03:04 PM


heres some reading material

fairbank56 08-13-2011 03:16 PM

Copper strap is a very poor choice for a bonding system if you so choose to have one. Since the copper straps go to the aft section of your boat and aren't connected to anything there, it's likely that there was an HF antenna tuner there at one time that the straps would have been connected to. Bonding is a controversial subject. It's use has to do with managing destructive galvanic and stray currents. The term, "electrolysis", while commonly used, is a misnomer in this regard.


mitiempo 08-13-2011 04:47 PM

The problem with bonding all underwater metal is that seacocks are all of one metal and don't really need protection. In today's marinas with both AC power on boats and shorepower everywhere, not always in good condition, this invites the seacocks into an electrical mix that can cause problems they don't have if not bonded.
The link posted above to an article by Stan Honey explains it very well. Here it is again. Grounding

fairbank56 08-13-2011 06:17 PM

Ah, but the water going through that seacock is conductive and therefore a stray current path may very well be provided through that less than desirable "connection". Better to have a good clean solid wired connection than not? There may also be a current path on the inside of the hull because of moisture on the inside of the hull. Not saying I'm for or against bonding but there are pro's and con's to both sides.


kd3pc 08-13-2011 08:22 PM

most likely a counterpoise for an SSB or Ham radio rig...tape/foil is of no use in bonding for the long term..


brokesailor 08-13-2011 09:06 PM

I do have an SSB Radio though I have not been able to get it to receive anything. I guess the copper strips go from it up to the thruhulls at the companionway. I guess I need to dive behinfd the engine and do some more scoping out. I am just surprised that nothing is connected to the grounding plates.

Kwasiemoto 10-28-2011 12:27 PM

I have just installed a 2" copper tape for my HF radio, and just as I started to make the connection to the thru hull, I noticed a small yellow spark. I mesured the ciurrent and found it to be fluctuating , but seemed to be around .68 volts. I hope someone has a explanation for why this has occured. There is no power going to this tape.

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