Bonding of through hulls

[swhfire21]

It seems that there is a lot of conflicting views on whether or not to bond through hulls and other electrically isolated items. My "new'ish" to me boat seems to have a mix of bonded and unbonded items. Also, the workmanship (or maintenance) of the bonding that was in place is poor at best. If I understand the latest thinking on this:

A through hull that is not electrically connected to anything else is best left unbonded.

The rudder & skeg (metallic) need to be bonded together with zincs in the circuit as there are likely different metals that are electrically connected.

A zinc needs to be provided on the prop shaft to protect the bronze propeller from the stainless steel shaft (it looks like shaft is isolated from boat by a shaft saver).

Is this correct? if so, I have a bunch of ratty looking wire I can pull out of the bilge, etc...

Thanks,

[Last Call]

When I had my 25D hauled for painting the bottom last fall, I found the founding plate on the hill was gone. Investigating I found the bolts that had held it in place were gone. Shell from barnacles apparently was the only thing plugging the holes. Scared the hell out of me. I went into the bilge and found that about 1/3 of the bolts were still in place and held onto the inner plate/wires. I had had a slow leak and thought it was water coming in from rain but now feel it was this plate and bolts missing. At any rate, I thought about replacing the grounding system and on calling the repair person in the area was quoted a price of $5000.00. Yes, you read that right. As this seemed excessive to me and as I had had many (14) boats through the years none of which had a grounding system... I elected to disconnect the whole thing. An additional problem that was discovered was that the missing plate had reversed the flow of electrons to the through-hull fittings which had pitted.
I felt that the danger of a lightning strike was less of a problem than the boat sinking due to a bolt being eaten away. I now rely on the zinc on the prop and a zinc 'fish' hung overboard. So far no further putting of the through-hulls.