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Discussion Starter · #1 ·
Our 1989 PSC34 has a dyna plate attached to the hull. The new electronics I m installing on board are calling for attachment of an RF ground...the power cables have three wires: Positive, Negative, and RF ground.

The manuals specific attaching RF ground to an RF grounding system or the negative terminal of the battery.

Would attaching the rf ground wires to the Dyna plate suffice?

Wouldn't attaching the rf ground wire to the negative bus bar be the same as attaching to the negative terminal of the battery?

Are there any other methods to create an rf ground to attach all the rf ground wires too?
 

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The dyna plate is a typical RF ground especially for the SSB. What type of electronics are you installing that need the RF ground?

Attaching to the negative bus bar is similar to but not as good as connecting directly to the battery. The battery will do a marginally better job at sinking the RF currents.
 

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Discussion Starter · #3 ·
My VHF, Multifunction Display and autopilot require separate RF ground. I was think about connecting to the plate but I am a bit concerned about the fact that the mast is grounded there and that a lightening strike would kill everything attached.
 

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Discussion Starter · #4 ·
My VHF, Multifunction Display and autopilot require separate RF ground. I was think about connecting to the plate but I am a bit concerned about the fact that the mast is grounded there and that a lightening strike would kill everything attached.
 

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My VHF, Multifunction Display and autopilot require separate RF ground. I was think about connecting to the plate but I am a bit concerned about the fact that the mast is grounded there and that a lightening strike would kill everything attached.
Are you sure your mast is grounded to the dyna plate? I have some knowledge of RF but am not an expert. However, I believe the RF ground and the lightning protection system should be separate as they serve very different functions.
 

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The issue here is different from the RF ground appropriate for an SSB. The cables that interconnect your electronics are shielded to minimize the potential for radio frequency interference (RFI). RFI may cause data disruption. Autopilots are particularly prone to unfortunate responses to RFI. Stories of 90 degree turns when a radio is keyed abound.

In your case connecting the shield to the battery negative will be most effective. Unless you are confident that you can avoid ground loops you are best served using the negative bus bar for the shield connections.

In the long term you should understand ground loops (bad) and single point grounds (good). Realize that there are a number of ground systems on your boat: DC ground (battery negative), AC safety ground (the green wire), AC neutral (the white wire which may will have a connection to the safety ground at inverters or generators), RF ground, a lightening ground (apparently on your boat but not on all), and possibly a galvanic bonding system. There are relationships between the various grounds and the interconnections should be in association with a single point ground.
 

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Discussion Starter · #8 ·
Each one of my chain plates hence the mast are hardwired to the dyna plate. I think I am going to stay away from attaching RF ground to the plate and stick to the negative bus bar ie, the negative terminal of the battery.
 

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Each one of my chain plates hence the mast are hardwired to the dyna plate. I think I am going to stay away from attaching RF ground to the plate and stick to the negative bus bar ie, the negative terminal of the battery.
That's probably the best solution. Again, I question whether the chain plates, etc. are connected to a dyna plate. More likely they're connected to a normal grounding zinc.
 

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Discussion Starter · #10 ·
I replaced every chain plate on the boat in February and attached to each was infact an 8 gauge wire that ran from the backing plate to the dyna plate which is on the starboard side of my boat.

Today I did some rewiring so I could finish the install of my auto-pilot. Back in 1989 they really thought Loran was going to be around forever....took me a while to cut all the tie wraps to release the dead end loran cable which is where I ran power to my Seatalk network from.

As for the RF ground, I found a 8/0 ground cable that I believe goes directly t the battery that I am going to use for my RF grounding. I am installing a bus bar so all my electronics that need RF grounding can be attached. Thanks for all the input on this subject it has been a real help.
 

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" and attached to each was infact an 8 gauge wire that ran from the backing plate to the dyna plate "
A common but dangerous mistake. Dynaplate (assuming it is a genuine one) is made of sintered bronze. It is porous, and that means there is a lot more "surface area" where it contacts seawater, in the pores. It also means that if it takes a lightning strike, that trapped seawater superheats, flashes into steam, and can literally explode the plate. And punch a hole in the hull.

Not a good thing.

So IIRC Dynaplate themselves say to use it as an RF ground, but not tied into the lightning ground. That should be a direct path into the water. A solid bronze or copper plate would be fine--but sintered bronze should not be used.

Using the Dynaplate as an RF ground means you can debate your bonding or ground system and connect or disconnect things as you please, while still having a separate dedicated RF ground.

Of course the whole question of bonding versus grounding is a bit more controversial than asking for the names of god.
 

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Discussion Starter · #13 ·
Dynaplate Grounding Shoes

"Safety Benefits of Proper Bonding and Grounding
A proper bonding and grounding system using Dynaplate grounding shoes will not reduce the chances of a lightning strike on your boat. It will, however, reduce the possibility of severe hull damage and electrical shock potential. A proper bonding and grounding system using Dynaplate shoe(s) will help provide a direct, controlled high-capacity path for lightning dissipation."

I pulled this directly from the Guest web site. Hush was built by PSC and designed by Crealock...I did not alter the system and attach the plate to the stays...are you saying the plate should not be used????
 

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Hush-
I would suggest checking with Dynaplate directly. From what I've read over the years, if PSC and Crealock said to bond it into the lightning ground system--they made the common misassumption.

WG-
Any surveyor that posts a "lightening" page, ought to be talking about jetsam, not the stuff Zeus throws. Just saying.(G)
 

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Discussion Starter · #15 ·
After reading a variety of articles and the posts here I think the next time Hush is out of the water I will be replacing the Dyna plate with something more suitable to ground the mast. I will move the Dyna plate further aft, nearer my electronics suite and then use the Dyna plate for an RF ground.....
 

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Dynaplate Grounding Shoes

"Safety Benefits of Proper Bonding and Grounding
A proper bonding and grounding system using Dynaplate grounding shoes will not reduce the chances of a lightning strike on your boat. It will, however, reduce the possibility of severe hull damage and electrical shock potential. A proper bonding and grounding system using Dynaplate shoe(s) will help provide a direct, controlled high-capacity path for lightning dissipation."

I pulled this directly from the Guest web site. Hush was built by PSC and designed by Crealock...I did not alter the system and attach the plate to the stays...are you saying the plate should not be used????
But did Crealock design the lightning grounding system and did PSC install it ?
And was it designed and installed correctly ?

The lightning ground was an option as was the RF ground.

Even on my purchased new in 1989 direct from PSC, PSC hired a rigger to install the rig and take care of a number of other details prior to and after the launch. Their normal rigger had been sent to to Florida to take care of some issues so someone else did this work. When the mast was pulled many years later I was not so impressed with the electrical work which relied on black tape to hold the twisted wires together.

On Crazy Fish I need to check on the lightning ground going to dynaplate. My memory has it running to the keel bolts but I could be wrong.

The SSB/Ham RF ground consists of dynaplate and a web of copper foil that was installed in the hull prior to the final layer of glass.

Regards

Marc Hall
Crazy Fish - Maintaining, Upgrading and Sailing a Crealock 37
 

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Discussion Starter · #17 ·
Crazy Fish, I found the dyna plate connection when I replaced the chainplates. Each chain plate had a grounding wire that is directly attached to the plate which is installed on the starboard hull nearly underneath the hanging locker.
 
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