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Old 19-01-2018, 21:51   #1
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HF Ground on a steel boat

I have almost completed installing my HF radio on my first steel boat (SEA 225). The owners manual says "connect the ground to engine or keel bolt".
Can I connect to my hull (grind paint, connect then repaint)?
I have tried to read articles but each time became totally confused by technical jargon.
The radio and auto tuner were previously installed on a GRP boat with an earth plate and I never had problems with signal, transmit or receive.
Will this work well or is it a case of suck it and see?????
Cheers, Paul
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Old 19-01-2018, 22:33   #2
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Re: HF Ground on a steel boat

Connect to the hull at any convenient place. You may want to put a series capacitor in your ground connection -- this will depend on your boats power grounding system configuration. We can point you to some resources that discuss the grounding issues, but in general a steel hull makes an excellent radio ground.
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Old 20-01-2018, 10:11   #3
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Re: HF Ground on a steel boat

I have a steel boat with an Icom 802 and the ground is a piece of alternator cable attached to the ATU and bolted to a convenient hull stringer. It works really well.

Be aware
+1 what Paul KLien says re grounding

My vessel is floating earth and we eventually found that the ground connection on the 802 also sends 12 volt to the hull which is a big no no on a steel boat. We have fitted a capacitor to stop this happening. I believe Icom may sell the capacitors but last time I looked I could not find a reference to it.
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Old 20-01-2018, 13:02   #4
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Re: HF Ground on a steel boat

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Originally Posted by Triumphant View Post
I have a steel boat with an Icom 802 and the ground is a piece of alternator cable attached to the ATU and bolted to a convenient hull stringer. It works really well.

Be aware
+1 what Paul KLien says re grounding

My vessel is floating earth and we eventually found that the ground connection on the 802 also sends 12 volt to the hull which is a big no no on a steel boat. We have fitted a capacitor to stop this happening. I believe Icom may sell the capacitors but last time I looked I could not find a reference to it.
Thanks for the reply. I will look into capacitors before I make the final connection, regards, Paul
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Old 20-01-2018, 13:05   #5
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Re: HF Ground on a steel boat

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Connect to the hull at any convenient place. You may want to put a series capacitor in your ground connection -- this will depend on your boats power grounding system configuration. We can point you to some resources that discuss the grounding issues, but in general a steel hull makes an excellent radio ground.
Thanks for the reply Paul
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Old 20-01-2018, 23:15   #6
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Re: HF Ground on a steel boat

Here is a good article on boat grounding, and those capacitors I mentioned: https://sailmail.com/wp-content/uplo.../Grounding.pdf. This stuff isn't specific to steel boats -- any boat with metal in the water (props, through-hulls, etc) can have grounding problems.

For what it's worth, my boat has the radio tuner ground connected to the ground system without any blocking capacitors, and I've seen no accelerated zinc erosion or other similar issues. But your boat could very well be different in this regard.
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Old 21-01-2018, 11:21   #7
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Re: HF Ground on a steel boat

Thanks again Paul
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Old 21-01-2018, 21:13   #8
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Re: HF Ground on a steel boat

Where to connect an RF ground on a metal boat?
The hull of a metal boat makes an excellent RF ground plate (aka dyna plate) but please, never, never, never connect ANY ground directly to a metal hull.

There are two schools of thought, on wooden and glass boats, about whether to ground or not to ground metals such as seacocks, gudgen pins and other underwater metal, but such discussions having no relevance to the question of RF grounds.

Metal boats always use a floating ground system, as do some glass boats. A floating ground system is where each DC ground is routed back to the batteries, using dedicated ground wires.

If your engine has only 1 wire to the tach, and temp, and altinator, and starter, and your ground return is bolted directly to the engine, then you do Not have a floating ground system.

If, however, you have TWO wires to each item, then it is likely you have a floating ground.

In both floating and non floating systems, there must be a path - directly or indirectly - for the heavy starter current to return to the battery. Both systems will have a heavy return cable bolted to the engine but, in a floating ground system, there will be a high capacity solenoid between engine and battery ground. This solenoid is energized only during the time the engine is actually cranking. As soon as the engine starts and the key is released, the ground solenoid is de-energised and battery ground is no longer electrically connected to the engine.
On a floating ground system, this is the only time that the battery ground is connected to the engine block.

Metal boats don't need dyna plates - the whole hull is a "dyna" plate - and must be connected to RF ground through a capacitor, or bank of paralell capacitors. RF goes directly through the capacitor(s) which block the DC.

Two comments about the multi capacitor buss bar:
1. It should be in a place for easy service and frequent inspection.
2. It should be constructed of two different metals - copper to which the copper ground cable and one end of the capacitor is attached and either an alumimium or steel sacroficial piece which to which the other end of the capacitor is attached and which in turn is bolted to the hull. These aluminium or steel sacrofical pieces are used so that the inevitable electrolysis is limited to the outboard junction of capacitor to sacrificial metal, and not to the actual hull.

Are these precautions necessary on steel and aluminium boats?Yes.
Corrosion on a metal boat is one thing. Electrolysis is a very different animal.
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Old 22-01-2018, 06:38   #9
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Re: HF Ground on a steel boat

Do some research on "single point ground." All will be revealed. *grin*

This is particularly important on metal boats to avoid galvanic corrosion (bad for the boat) and ground loops (bad for radio performance).

Forgive me for being brief - I'm jammed and can only self-justify a short break. Drop me an email at dave@auspiciousworks.com and I can send you a bunch of links.
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