This conversation here is trying to talk about four distinct electrical systems on a boat at the same time.
The DC system,
the bonding system,
the AC system,
the lightning shield.
If you are going to make any sway with an absolute dunce like me, we have to keep the terms straight. Confusion reigns.
Gut feeling and some evidense (eg Mr Amos in the aforementioned article - one of the experts disagreeing amongst themselves) suggests that each system should be independant, This does not seem possible at the moment.
1>Therefor, the batteries, motor and dc wiring have a single ground that is separate from the bonding system. Isn't this an 'active' system, while the bonding is a 'passive' one? So why would you ground the dynamic electric system to a thruhull?
2>The bonding circuit supposedly equalizes stray currents to protect metals from galvanic action. Why doesn't this circuit have its own ground or earth? It can't, I guess, because it'll get confused like the rest of us! So what they do on frp boats Now is Unbond and Isolate all important metal pieses from each other. Is this not so? 338 has all its bonding wires torn out!
3>Bringing shore power aboard is asking for trouble for many reasons. It must be isolated from the boats dc wiring, no? So why can't some real smart sparky create a little box that makes sure the charger Never can short over to the the dc ground. The AC grounds on shore, right? There has to be some kind of simple interuptor that will protect the ship. I really must be persuaded that shore power is necessary beyond an inconvenient extension cord!
4>Why connect the precious metals on the boat for lightniing protection? You want to create as unmistakable a path to the earth possible, No? So, don't you have a bottlebrush disapator up top as first defense and from there as straight a route down the shrouds to the water with fat copper as a hopeful dissuader? But the point is, isn't it, that you don't want to encourage a million volt hit to visit a boat that is an interconnected circuit?
(LATER EDIT): BB masttop disapators have lost favor. Maybe good for keeping gulls away!
Can't I have four separate systems?
Pretty soon there is going to be another nice little electronic box that will create a negative ion coating on inwater metals for OBs and propellers and thru hulls called a 'cathodic protection system.' It'll have a galvanic isolator chip for your ac and dc ground separation. It already exists but they haven't miniaturized it yet. Look for it at yer spring boat show.
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LATER EDIT (3/2017): Seems to me that ole blowhard here did bring up some anomalies...
But here is a site with a great article on electrolyis for boats that live in the water. From a cruiser's standpoint.
"Never create a circuit unless you absolutely have to.' 'Zincs create electrolysis'. 2nd thoughts on ABYC common ground for DC/AC.
Electrolysis 101 http://yachtpals.com/how-to/electrolysis?page=1
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