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Earth/ground wire

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Brownemi View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brownemi Quote  Post ReplyReply Direct Link To This Post Topic: Earth/ground wire
    Posted: 12 April 2021 at 13:25
Hi readers, greetings from down under. I am a new H385 2012 model owner, and am following through on the buying survey report which found that the earth wires to the rear keel bolt were needing to be reconnected.

I did an advance search and saw the posts that Hanse recommended this and the newer, conflicting 418 thread  that said Hanse are now reconnecting/bonding earth wires to both keel and rudder in the last few years. Nothing is straight forward is it WinkMy boat has a galvanic isolation unit, but it is kept on a swing mooring far away from any shore power or marinas. I rely solely on DC only.

First question, do I need to reconnect the wires or not? Secondly, I am upgrading the standard 350w inverter to a larger pure sine wave 1500w unit and I should ground the case.  If the keel isn’t grounded, what then is the ground point? It may be a naive question being no expert on marine electronics, but the surveyor said reconnect the keel ground, whilst the boat broker said no I didn’t have to.

Thanks for your anticipated patience,

Yours confused
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Captain Cook View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Captain Cook Quote  Post ReplyReply Direct Link To This Post Posted: 12 April 2021 at 22:25
Jefa is the manufacturer of rudder and steering, so read their advice on the Jefa homepage.
I would never connect the rudder to the boats ground/keel/-engine.
On my 400 I had a small amount of corrosion on the rudder, because I had painted with copper-paint too close to the rudder.
To stop this I made a copper-free zone Ø30 cm around the rudder shaft, and I connected an aluminium button-anode to the aluminium rudder. This anode has a Ø15 cm copper-free zone, and is ONLY connected to the rudder.
Do not use zinc anodes to alu, because alu is more reactive than zinc. Use alu or magnesium.

Freya H400 #27 (2006), 40HP 3JH4E, 2-cabin, 3-blade Flexofold, Aries LiftUp Windvane, Exturn 300, Jefa DD1,Simrad NX40,Icom M603(VHF)+M802(SSB)
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Carlosailfan View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Carlosailfan Quote  Post ReplyReply Direct Link To This Post Posted: 13 April 2021 at 06:48
Hi Captain Cook,

Confirm your story,
i had exactly the same issue as you describe, my dealer painted the copper coat on the rudder and guess, minor damage to the rudder shaft. I removed the coat and installed an anode only for the rudder and now it is fine :).
Best regards
/C
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Brownemi View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brownemi Quote  Post ReplyReply Direct Link To This Post Posted: 13 April 2021 at 12:16
thanks Captain and Carlos, I appreciate your comments and will definitely look at the rudder situation.

Back to my other questions, does the earth wire need to be connected to the keel and if I ground a new inverter to its case, will it be grounded if the keel earth wire remains disconnected?

Any thoughts please?


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350Bob View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 350Bob Quote  Post ReplyReply Direct Link To This Post Posted: 13 April 2021 at 12:20
if anybody has any pictures of how they installed the rudder anode I would be really grateful if you would share them please.

Many thanks

Bob
H350 #205
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Carlosailfan View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Carlosailfan Quote  Post ReplyReply Direct Link To This Post Posted: 14 April 2021 at 06:42
Hi Bob, i have no ground wire attached to the rudder but a thick cable to the anode. The anode itself is not the classic small one they put on in factory but an bigger version with more surface, and yes maybe an overkill.
In the Hanse shop you will find the factory version they put on + the bolts, think this works also fine. I have somewhere a picture and i have to look for, there you can see the place of installation. In general not a rocket science seen most important is, nearby the rudder to keep the wire to it short and accessible form the inside to access the bolts in case of. ( and of course under the waterline :) )

I discover they offer also a larger internal plate ( in green ) with 2 bolts on it to go through the hull, this i made myself out of stainless steel and installed on ours, it works fine, to see @ the erosion of the anode :).
If i can find the pictures i post them.

Stay safe !!




Best regards
/C
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350Bob View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 350Bob Quote  Post ReplyReply Direct Link To This Post Posted: 14 April 2021 at 21:51
Hi Carlo,

Many thanks for the reply and pictures.

Bob
H350 #205
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Downeaster View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Downeaster Quote  Post ReplyReply Direct Link To This Post Posted: 15 April 2021 at 21:34
Originally posted by Captain Cook Captain Cook wrote:

Jefa is the manufacturer of rudder and steering, so read their advice on the Jefa homepage.
I would never connect the rudder to the boats ground/keel/-engine.
On my 400 I had a small amount of corrosion on the rudder, because I had painted with copper-paint too close to the rudder.
To stop this I made a copper-free zone Ø30 cm around the rudder shaft, and I connected an aluminium button-anode to the aluminium rudder. This anode has a Ø15 cm copper-free zone, and is ONLY connected to the rudder.
Do not use zinc anodes to alu, because alu is more reactive than zinc. Use alu or magnesium.


Zinc is fine for protecting aluminum alloys in salt water.  The table you show is for the pure metals.  Rudder stocks, outdrives, etc. are all of high quality aluminum alloys. 
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Carlosailfan View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Carlosailfan Quote  Post ReplyReply Direct Link To This Post Posted: 19 April 2021 at 07:10
External position of the Rudder Anode. Could not take a picture from the inside at the moment seen all material is in.

Best regards
/C
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davidla View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote davidla Quote  Post ReplyReply Direct Link To This Post Posted: 25 October 2021 at 14:01
Hi,
This is an old post but one that bears answering.  Firstly when you talk about an earth wire, we are referring to AC electricity.  No earth or ground exists in DC electricity.  Yes I know there are lots of diagrams showing a "ground" in DC but in reality this is just a return wire to the negative terminal.  Don't believe me?  Disconnect your negative terminal from the battery and then see if you still have a ground.  Yes this includes your engine block.  It is just a big ugly source of resistance back to the negative terminal.
Now AC is different (sort of).  Firstly a ground wire is not required for AC to operate properly.  There is a hot wire and a neutral, akin to the positive and negative of a DC circuit.  The ground wire is there to protect people by causing a protective circuit device (RCD, GFCI ELCI) etc etc to trip if there is a fault in the AC circuit.  This is because the neutral and the ground wire are connected at the source (probably in a transformer somewhere close by your house, or in your inverter or generator on your boat.) and if there is a mismatch between the current flowing through the hot wire and through the neutral wire this is detected and power is cut.  

Note the ground rod in a house does not protect people from electric shock.  It is there to divert lightning strikes to ground nothing more.

Electricity starts at the source, goes to the load and then goes back to the source.  This is true of all electric circuits in normal operation.  As noted above in the case of lightning there is no attempt for the electricity caused by the lightning to return to the source - hence the rod into ground in an attempt to neutralise the strike.  Good luck with that!

Back to AC on a boat, if the electron flow starts at the source it must return to the source.  If the source is an inverter, it is arguable if the source is the inverter or the battery from which the original supply came.  I presume this is why the advisors at the ABYC dictate an extra battery negative cable be connected from inverter case back to the battery.  (The inverter actually connects the AC ground wire to neutral see below.)

In the case of a generator the source is exactly itself.  Therefor AC must return to the generator.  Now if you connect a ground to your generator where will it flow to exactly.  Should you connect it to a keel bolt to harmlessly disperse rogue electricity into the water?  Remember, electricity starts at the source and returns to the source.  If your system generates a ground fault, it will cause an imbalance in the current flow of the hot and neutral wire.  This would trip an RCD  and stop the flow.  This can happen if you have an earth wire connected AT THE SOURCE. It doesn't matter if you have a ground wire connected to anything else as long as the ground fault is triggered and the protective device cuts the power.  THIS IS THE IMPORTANT BIT.  Always have an RCD after your AC source so you can automatically cut the power in the event of a ground fault.  Do not rely on any earth wire to save lives by having it connected to something on the "outside" (we are talking GRP boats here).
When you plug in at the dock the RCD is on the pedestal at the marina, away from the dock you need to be sure your RCD is working - test it often.

Now, if you do put AC electricity into the water from a ground fault where will it go?  Answer: It will try to get back to the source IE on your boat.  To do this it will attempt the path of least resistance.  This might be any piece of metal below your waterline which is the lowest point of resistance back to the source.  Rudder stock, propeller shaft you name it.  Got all your through hulls bonded together with a nice piece of copper wire.  Great path for stray currents.  If you have a circuit interrupter (RCD) then don't worry about it, the electron flow will be cut.
Good luck

Please note I am not a qualified electrician, so I don't repair stuff.  I am not an electrical engineer so I don't design stuff.  I just test and verify what is important.

PS
Oh and that lighting strike on your boat?  Read up on the electromagnetic pulse (EMP) from a lightning strike and stop worrying about it.  No amount of grounding your mast with a 10awg wire will stop the pulse.  Just have insurance that covers you.
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