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I confess I don’t quite get the difference between a boat’s negative “ground,” which ultimately connects to
the negative battery terminal(s), and the boat’s sea “ground” that ultimately connects to the surrounding
water. I know they’re not the same and, according to some “experts,” should be kept separate in the vessel’s
wiring system.I’m installing a SSB. I’ve “grounded” the automatic antenna tuner to a few bonded bronze thru-hulls with a 3″
wide copper strap, and will extend that connection to the keel’s lead ballast next via a lag bolt, as some of
you have recommended. The transceiver’s manual recommends also “grounding” the radio to the “water ground” (as
opposed to the negative battery ground). Since I can’t get a 3″ copper strap to the nav table without some
ridiculous antics, I thought I’d make that connection with a 6 AWG cable from the radio to the central
green-wire bonding ground strip on the connection panel in the back of the locker aft of the nav station, the
shortest possible run from the nav station. But when I studied that panel, I found that Pearson had connected
that green-wire terminal strip to the negative battery “ground” strips above it with jumper cables, so the
whole thing is one. A marine electrician tells me that’s wrong, that the two “ground” systems must remain
separate or you’ll have electrolysis problems. Shit! Pearson sure didn’t know that. They even ran half a dozen
green wires, which are presumably water ground thru-hull bonding wires, to the upper,
negative-battery-terminal ground strips. Pearson also bolted several thru-hull green wires directly to the
V-drive and transmission, which finally lead to a heavy stud sticking up from the hull just beneath and to
port of the transmission. First time I ever noticed that stud. I guess it’s a water-ground.Today I re-routed all the green wires to the bottom-most ground strip on that aft locker panel, and removed
the jumper cable between that “green” terminal strip and the “black” strip above it so that the green-wire
terminal strip is no longer joined to the two black-wire negative ground terminal strips. So I’ve effectively
separated the green- and black-wire “grounds” (except maybe for those green-wire connections to the V-drive
and transmission, since that machinery must be electrically connected to the engine block, which is definitely
connected to the negative ground system). Oy!Anyway, I think this separation is the right thing to do. Now I’m going to run a 6-AWG cable from the ground
terminal on my SSB transceiver to that green-wire, underwater ground terminal strip, figuring that’ll “ground”
the friggin’ radio to the underwater ground as per the manual’s instruction. But first I’m going to have a
stiff sundowner.What do you smart guys think?
Thanks,
Tor
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Silver Heels, P-424 #17
http://www.SilverHeels.us
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Hey Buddy…. how ya doing. Just wanted to let you know I made it to the
Bahamas. I am currently in Coral Harbor on New Providence. I hope you are
enjoying the weather down there cause it sure sucks here. Why did I leave to head
north?Any how I’ve already had my sundowners so I am not fit to answer all
your questions. I will let the big boys answer that. Adding a ground plane to
your SSB is like talking anchors though, everyone will have 2 opinions.
You need to learn the difference between BONDING and GROUNDING. I have my SSB connected to an UNBONDED though hull which is attached to some copper foil in the bilge BUT i am going to change that to just using some radials…..
I am sure John or Bob can do a much better job at explaining all this….
But I am sure this will at least start the debate going…
alan
http://www.sailblogs.com/member/unabated/— On Mon, 4/26/10, Silver Heels <> wrote:
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Tor
Its quite a complicated subject. Think of it as Voodo. At its simplest,
consider that the frequencies you expect your transceiver to operate vary
from as low as about 4mhz to as high as about 170 mhz. The wavelengths vary
from about 250 feet to about 6 feet. Remember that electricity travels at
the speed of light, so even though you might have a DC connection with zero
ohms to your battery ground, the radio frequency (AC waves) that travel
through your wires to your bonding system have at least a fraction of a wave
in the wire and perhaps several waves. You can’t think of something as
being well connected just because the wires are hooked up and your ohmmeter
says zero ohms. To make things more complicated, just because your ohmmeter
says you aren’t connected to something doesn’t mean radio frequency (RF)
signals won’t be connected. As an example, you can have an RF connection
through the fiberglass hull of your boat between a good ground strap and the
seawater. To make matters worse, there are pleanty of differing opinions on
the right way to connect your grounds. Here’s a good free publication on
the subject.http://www.sgcworld.com/Publications/Books/hfguidebook.pdf
I’m not sure I agree that the AC bonding system and DC ground system should
be separate. I think they should be connected at as few points if possible;
ideally one. Most people use the engine block for that connection, but your
antenna tuner and transceiver need both an antenna and DC ground too. I
have a heavy gauge cable running from my engine block up to my nav-station
to act as a radio ground. From the engine block, I have ground radials run
through my bilge. Pearson connected all the through hulls with ground
wires, but that’s not enough for an RF ground. For RF groundsMost folks agree that big flat conductors with lots of surface area are
better RF conductors than round cables. You can buy copper foil made for
purpose of creating an RF ground plane in your boat or you can buy copper
flashing. The stuff has sharp edges so wear gloves. Run a bunch of it in
your bilge as close to the seawater as practical. Glue it down with
something if you can; liquid-nails will do. Connect it to your engine
block. Run a fat ground cable from the block up to your nav station. Flat
braid cable is best if you can find some. Run another piece to ground your
antenna tuner. Cross your fingers and pray.Hope this helps
Regards
Rich – KE1EVQuote:
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Thanks, Rich. I know you know this stuff. For my part, I understood about
10% of what you said. Welcome to planet of the apes. I actually have that
SGC manual; it came with my SGC-230 tuner. It is written in Greek (or Geek,
which is much the same thing). You have to know to understand, and you have
to understand to know. Ketch 22 aboard this 424.My German neighbor in this Grenada anchorage is a professional marine
electrician and an obviously sharp guy. He’s the one who advised me to
separate the two ground systems. It makes at least as much sense as all the
other opinions I’ve heard, plus this guy is a pro and really seems to know
his stuff. He said all the high-end European yacht builders today are
separating the two grounds as a matter of course; that when our Pearsons
were built builders just didn’t understand the difference. On the other
hand, what you have in your boat is obviously working. You’d know by now if
you were melting zincs at an abnormal rate.I’m pretty sure the way I’ve grounded the tuner is correct. Connecting the
radio as I described seems adequate from what I’ve gathered, i.e., lots of
copper from the transceiver to bonding wire central, from which many more
copper cables go to bronze thru-hulls and thence directly into the sea. I
can’t imagine a more direct radio to ground connection short of draping a 4″
strap over the cap rail.Anyway, thanks for the feedback. I’ll let you know if what I’m doing works.
Tor
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Silver Heels, P-424 #17
http://www.SilverHeels.us
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He’s just telling you that the Europeans who have traditionally combined the
AC DC grounds are now doing it the way the Americans have all along.-p
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s/v Deep Playa | Pearson 424 Hull #152 | http://www.DeepPlaya.comOn Mon, Apr 26, 2010 at 6:47 PM, Silver Heels <> wrote:
Quote:Thanks, Rich. I know you know this stuff. For my part, I understood about
10% of what you said. Welcome to planet of the apes. I actually have that
SGC manual; it came with my SGC-230 tuner. It is written in Greek (or Geek,
which is much the same thing). You have to know to understand, and you have
to understand to know. Ketch 22 aboard this 424.My German neighbor in this Grenada anchorage is a professional marine
electrician and an obviously sharp guy. He’s the one who advised me to
separate the two ground systems. It makes at least as much sense as all the
other opinions I’ve heard, plus this guy is a pro and really seems to know
his stuff. He said all the high-end European yacht builders today are
separating the two grounds as a matter of course; that when our Pearsons
were built builders just didn’t understand the difference. On the other
hand, what you have in your boat is obviously working. You’d know by now if
you were melting zincs at an abnormal rate.I’m pretty sure the way I’ve grounded the tuner is correct. Connecting the
radio as I described seems adequate from what I’ve gathered, i.e., lots of
copper from the transceiver to bonding wire central, from which many more
copper cables go to bronze thru-hulls and thence directly into the sea. I
can’t imagine a more direct radio to ground connection short of draping a
4″
strap over the cap rail.Anyway, thanks for the feedback. I’ll let you know if what I’m doing works.
Tor
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Silver Heels, P-424 #17
http://www.SilverHeels.us
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Owners no more...
Thanks Dawn and Patrick! -
Maybe, Pat, but he and I were talking specifically about the separation of
the green-wire ground from the black-wire ground at the time. I believe
that’s what he was referring to when he made that statement. But then again
all this is magic to me, so who knows?Tor
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Silver Heels, P-424 #17
http://www.SilverHeels.us
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*Grounded*, the negative side of the DC system. Main Negative bus should be
a terminal strip and not the engine block.*Grounding*, the vessel bonding system which is tied to the main negative
bus at a single location. These are NOT load carrying conductors.*AC Grounding* bus (the green wire) is also connected to the main negative
bus.*AC Neutral* is only connected to AC ground at the power source.
I can’t offer theory or what if’s, this is straight from E11. Let me know
if I got any of it wrong.Chuck
On Mon, Apr 26, 2010 at 10:11 PM, Silver Heels <> wrote:
Quote:Maybe, Pat, but he and I were talking specifically about the separation of
the green-wire ground from the black-wire ground at the time. I believe
that’s what he was referring to when he made that statement. But then again
all this is magic to me, so who knows?Tor
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Silver Heels, P-424 #17
http://www.SilverHeels.us
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My comment was about connecting the DC ground to the RF ground plane. The radio equipment typically connects them internally. In theory, it would be possible to put in a transformer that would separate them, but I see no advantage. Sorry if my discussion was confusing. The subject of RF ground planes is too complicated to explain in a short mail message. My suggestion is to have someone who is qualified advise you on how to hook this stuff up.
With regard to the AC ground (green-wire in your shore power cord), I do not have my DC ground connected to this. I don’t want stray AC current getting into my shaft zincs.
Rich
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Tor,
At the risk of giving you more options than you want or need, you might
consider installing radials for your RF ground plane instead of or in
addition to the copper foil. That is what I’m running off after having
great difficulty getting good connections to Winlink and SailMail on our way
to the Azores in 2005. When we were in Horta a friend (who had installed
the copper foil ground for me) suggested adding radials to SGC ground. He
provided all sorts of suggestions on lengths (1/2 the wavelength of the
primary frequency) and material (12 AWG primary wire) to use, none of which
helped. I had some excess 1″ copper braid on board, so we strung a couple
of radials of arbitrary lengths off the SGC – one horizontal below the deck
back to the stern, the other athwart-ships down under the fuel tank, all of
this in the Port Cockpit locker. My crew was in the locker moving the
radials around while I tested several frequencies looking for decent SWR
readings. Eventually we found the arrangement that worked decently and I’ve
been running off that arrangement ever since.
This spring I discovered why the original copper foil ground plane did not
work so well. When I had hatches cut into the cabin sole under the table I
finally had access to the one area where the foil could not be secured to
the hull. Here is what it looked like:
http://www.svsarah.com/Sarah/Images/TableHatch8.JPG.
Salt water from removing and replacing the knotmeter sender collected on top
of the copper foil and dissolved it. So if you are installing foil make
sure you keep it out of the way of any saltwater or seal it with something
(e.g., epoxy)John
On Tue, Apr 27, 2010 at 9:53 AM, <> wrote:
Quote:My comment was about connecting the DC ground to the RF ground plane. The
radio equipment typically connects them internally. In theory, it would be
possible to put in a transformer that would separate them, but I see no
advantage. Sorry if my discussion was confusing. The subject of RF ground
planes is too complicated to explain in a short mail message. My suggestion
is to have someone who is qualified advise you on how to hook this stuff up.With regard to the AC ground (green-wire in your shore power cord), I do
not have my DC ground connected to this. I don’t want stray AC current
getting into my shaft zincs.Rich
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Hey John,
When it comes to electrical stuff, the devil is often in the terminology –
at least, for me. I thought radials were some kind of improved car tire…
that roll on the “ground”. 🙂Wow, that copper strap dissolves like Alka Seltzer in hot water. I ran my 3″
strap over the top of the fuel tank, down to its first thru-hull connection,
and then forward along what has so far always been dry areas in the upper
bilge. Will have to remember to inspect it from time to time, though. And
speaking of strap runs, I need to splice two sections of 3″ copper strap
together. I figured I’ll just place them together end to end and fold them
several times so that the 3″ width remains continuous. Is there a more
correct way?Tor
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Silver Heels, P-424 #17
http://www.SilverHeels.us
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Tor,
I haven’t attempted to join two pieces of foil together, but I think I would
put some solder in that fold to make sure your get a strong connection.On Tue, Apr 27, 2010 at 12:43 PM, Silver Heels <> wrote:
Quote:Hey John,When it comes to electrical stuff, the devil is often in the terminology –
at least, for me. I thought radials were some kind of improved car tire…
that roll on the “ground”. 🙂Wow, that copper strap dissolves like Alka Seltzer in hot water. I ran my
3″
strap over the top of the fuel tank, down to its first thru-hull
connection,
and then forward along what has so far always been dry areas in the upper
bilge. Will have to remember to inspect it from time to time, though. And
speaking of strap runs, I need to splice two sections of 3″ copper strap
together. I figured I’ll just place them together end to end and fold them
several times so that the 3″ width remains continuous. Is there a more
correct way?Tor
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Silver Heels, P-424 #17
http://www.SilverHeels.us
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John,
Just to add to the mix, I purchased on recommendation from someone I met in George Town, the KISS Radial Ground Plane. I ‘ll  install  it when I return to the Bahamas next month. I’ll let you know if I get any better results with Airmail. I’ll try it both with the foil and withoutWhen I was working (employed) we used RF Sealers to seal PVC (10 mil) together. The RF generators ran at 31.5 MHz at around 2000 watts. When we upgraded some of our logic components to IC’s we had a terrible time with noise. The only thing that worked to reduce the noise level was foil ground straps and lots of it. RF at that freq. travels on the skin or surface of the conductor. So thickness (cir. mils) of wire was of no value. Which is why braid works almost as well. Even though there a small dia. wire there is a lot of surface area in the braiding.
There was so much energy in the room that it would light 6 ft florescent tubes just by being there ( not hooked up to any wires).
The coax that we used was 1 1/2 inches in diameter.
alan— On Tue, 4/27/10, John Stevenson <> wrote:
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Those of you who have connected a counterpoise strap to the lead ballast beneath the mainmast step area, how
long a lag bolt did it require? How much fiberglass did you have to go through to reach the lead, and how deep
into the lead did you go?Tor
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Silver Heels, P-424 #17
http://www.SilverHeels.us
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hey Tor-
sounds like you’re into it man! anyway, use about a 3 inch brass or
stainless lag bolt/bolt. use 2 nuts to capture and hold the grounding foil.
you can tap for a 1/4-20 bolt, or just screw in a regular threaded lag bolt.
As I recall there is only about a 1/2in to an inch of fiberglass over the
lead. be sure to epoxy or otherwise seal the bolt well to prevent water
from going down into the encapsulated keel.good luck!
Rodd
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Hey Rodd,
Yes, into it at long last and nearly through it now. Quite the little
learning experience.Thanks for the tips. I don’t have a 3″+ tap, so I guess I’ll have to use a
lag bolt. I guess I’ll find out exactly how thick the ‘glass is when I drill
through it in the morning. Seems to me I’ve heard others say it’s 1-½” to
2″.Tor
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Silver Heels, P-424 #17
http://www.SilverHeels.us
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Rich
If the shore power is not grounded to the DC ground is it safe when you use
inverter or generator AC current? I read Calder’s book and he suggested
that hooking it up that way could be done yet he countered it later in the
same paragraph. What is the ground when not hooked up with a shore power
cable? I am asking out of ignorance. I understand enough to know I don’t
know like Tor said.Linus
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If everybody hooks up the green wire from the shore power cord to their DC ground, all the boats have their DC grounds connected together. All the zincs are connected and any boat that has electrolysis problems will share their problems with the other boats. I don’t think I want to be telling folks what’s best for them, but I decided not to do that. All the green wires inside my boat are still connected and they go to the engine block, but the green wire that comes in from the dock goes nowhere. Kind of makes me wonder why they put three wires in the shore power cords. Maybe folks who cruise in freshwater need the green wire.
Rich
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Breakers work by the current passing from hot to either neutral or ground –
it’s simply the amount of current passing through the breaker. Where the
circuit goes, it doesn’t care as long as current is passing through the
breaker itself.Don’t confuse AC neutral with ground or the bonding grounds from the DC and
AC grounds. In theory, they all have the same potential but in practice may
not.The neutral in AC varies in voltage just like the hot wire does. The
bonding ground in the boat makes sure that all the conductive materials like
through hulls, rigging, keel, strut, and engine don’t create essentially a
battery which will galvanically corrode everything.DC grounds are just the return to the battery from a DC load.
Since the engine provides a DC ground it is connected to the bonding system
and in theory that makes them the same, but the bonding system could be
isolated from the engine and still do its job. Some boats are set up that
way.Another purpose to the bonding system, in theory, is to provide lightning
protection. On the other hand, lightning doesn’t strike from above – it
connects to a ground leader so that the initial cause of a lightning strike
is current coming up from ground to meet the first downstrike allowing the
full strike to occur (lightning isn’t just one strike – there are a bunch of
them).From that, it follows that if your masthead is grounded it makes it a much
more favorable target for lightning because it provides the easiest paths
for the circuit. My theory is that not bonding everything to everything
makes you a much smaller ‘target’ for lightning because you’re not providing
a good ground to air path. The only downside to that is that you need to
keep track of your through hulls for corrosion.If you sail in fresh water, that’s not an issue as fresh water has a very
high resistivity to current flow and therefore galvanic corrosion. This
whole subject really makes a great case for Marelon through hulls and valves
as they are not subject to any kind of galvanic corrosion. Or any corrosion
at all.But I’ve seen grounded boats and non-grounded boats both get hit by
lightning so it’s up to you what you do. Generally, the grounded boats have
more and more serious damage, although I can’t say why. Lightning’s a funny
thing.I’ve typically kept my boats unbonded and haven’t suffered any unusual
corrosion.Bob
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Bob Fine
s/v Pelican
Pearson 424 Hull #8
http://thesailinglife.blogspot.com
Follow me at: http://www.tinyurl.com/WhereIsBobFine
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