Re: [electricboats] Grounding.

The amount of conflicting information is amusing, my goodness.  I can see that it will require setting aside some real time to sort out the guidance. 

On Dec 4, 2020, at 10:16, Bob Jennings <heatnh@gmail.com> wrote:



Tom,  forgot to mention. 

Thanks for mentioning ABYC E-30. 

I'll have to check it out.

On Fri, Dec 4, 2020, 1:03 PM Bob Jennings via groups.io <heatnh=gmail.com@groups.io> wrote:

Tom,  That's interesting ABYC E-30  doesn't want the propulsion system & their components grounded.

FWIW, I would not ground anything to a thru hull. That's just asking for trouble.

I took my thru hulls out of the "bonding" circuit.

You still want to protect your shaft, prop & strut if applicable with a anode. The shaft & prop are dissimilar metals. My drive is isolated from the shaft & I put a zinc on the shaft. It does protect the prop.

On Fri, Dec 4, 2020, 12:48 PM THOMAS VANDERMEULEN <tvinypsi@gmail.com> wrote:

This is not my field of expertise, but I'm inclined to agree with Daniel.  That is, I think of "bonding" in the context of lightning strike management and corrosion control; while "grounding" is something done with current-carrying circuits and components to manage/minimize stray current.  Daniel points out that the DC portion of a typical diesel auxiliary system is grounded to the engine block because that's the biggest hunk of metal.  You might also think in terms of a "chassis ground."  The AC portion of on-board systems is best kept separate from the DC portion as well as the bonding circuit.  As I build out my on-board systems, I expect to only on-board AC system energized when dockside.  So, my AC system will be grounded through a galvanic isolator to the shore-power ground.  The ABYC standard E-11.17 calls for the AC ground to also be connected to the engine.  But this only applies to diesel auxiliaries.  ABYC E-30, Electric Propulsion Systems, [30.8 Grounding] states: "The boat's propulsion electrical system (e.g. batteries, generators, inverters) shall remain isolated from the boat's grounding system."
In addition to the relevant ABYC Standards, I bought a copies of Nigel Calder's book, _Boatowner's Mechanical and Electrical Manual_; and Don Casey's book _This Old Boat_ and refer to each of them from time to time for these sorts of questions.

What's not yet clear to me, is exactly how to approach corrosion control of the prop and prop shaft.  Is a sacrificial anode sufficient; or indeed, even necessary if the propulsion system is not bonded to the boat systems?  I'm still researching that one!

[-tv]