What to bond to what?

[Dantodd]

Ok.

My AC and DC run on independent ground circuits connected at the engine block. AC neutral is NOT connected to any "ground" onboard. This is pretty straightforward and well understood.

What I am not sure of is exactly what to do for bonding.

My mast connects to a keel bolt, (steel keel) presumably for lightning protection.

My primary through hulls (not the sink or toilet drains) were bonded together at one time, but not to the engine, they were protected by a zinc fish connected to the portion of the back stay below the SSB. This kept them separate from the DC and the lightning protection connection. The SSB ground connected to the bonding system and it all ran on copper ribbon.

I know that many say binding is absolutely necessary and others say that by having nothing connected you get much less corrosion. I am trying to decide what to do to provide the most protection.

I am open to all suggestions.

My current (yuck yuck) plan is:

Install a shaft brush

Bond ALL through hulls with stranded copper, to the bottom of the SSB backstay and to the engine.

Keep AC and DC grounds on engine block.

Keep mast grounded to the keel bolt and use the keel bolt for the RF counter poise/ground using copper ribbon. (I know this will make the SSB more susceptible to lightning damage but I'm not sure how much difference that really makes)

Keep a zinc fish on the backseat in the harbor.

Is there anything I am doing massively wrong? Anything important that I am missing?

 

[Stu Jackson]

Have you seen this>\?

http://www.westmarine.com/webapp/wc...catalogId=10001&page=Marine-Grounding-Systems

 

[Dantodd]

Have you seen this>\?

http://www.westmarine.com/webapp/wc...catalogId=10001&page=Marine-Grounding-Systems

Thanks Stu, I hadn't seen that. I will definitely add the galvanic isolator to the AC side before I ground it to the engine block.

I am still not completely sold on not bonding through hulls. My boat lay fallow for a number of years and I suspect that he zinc fish, which was half corroded contributed to the good shape every through hull was in when I started refitting this winter. Any good sources for info on why one SHOULD. Bond the various through hulls.

 

[mitiempo]

I agree with Stan Honey, the author of the article that Stu linked to. The only reason to bond, if there is one, is if you are on a mooring and never visit at a dock with shorepower. Proper through hulls are made of one type of bronze which is not prone to dezincification - very unlike a propeller. And they are isolated. If you bond you are bringing them into a mix they should not be a part of. The real risk is the propeller.

As far as a shaft brush, unless you have a flexible coupling it isn't necessary. You can check this with an ohm meter measurement between the block and the shaft.

In your first post you say "My AC and DC run on independent ground circuits connected at the engine block." That means they are not independent and you should get that galvanic isolator.