Zinc Anode Troubles

[fstbttms]

Originally Posted by Lancerbye

I noticed that there is not much room for a collar anode in front of the prop. You might try pouring a zinc anode over the prop nuts. That is a common practice when you don't have enough room for collar anode.

Or he could go down to his local chandlery and buy this:

[senormechanico]

Originally Posted by ambloplites

Pete - bought it ... reading it ... sleeping with it under my pillow.

So, my zincs are attached to either side of the lower keel, just in front of the rudder, and just below the lower rudder bracket:

Attachment 74132

I cannot for the life of me understand how that protects anything, as it is not in physical contact with anything but the keel. Unless ... the keel is encapsulated iron, and the engine mounts are embedded into it?? Or am I completely missing how zincs function??

If I'm thinking right, the prop is an alloy of copper with zinc (some kind of brass) ... the prop shaft is stainless steel ... because they're both in seawater, zinc from the prop is going to "electrically leach" (for lack of more technical terms) out of the prop making it weak and useless. Unless there is a sacrificial zinc physically touching the shaft/prop system? The sacrificial zinc can't just be "close by" ... correct?

And this is what my prop looks like (hope the pics come through, they're not showing in my preview):

If you look carefully at your rudder photo, you will see a braided or stranded wire connecting the zinc to the rudder strap.
Imho, the prop damage on the trailing edge is not from hitting rocks, but from a lack of zinc protection.
Check with a multimeter on the ohms scale to see if there's any continuity to the prop shaft. (it should be only a few ohms, the less the better)
If there's no connection, optimally ZERO ohms, you need to bond, or have a separate prop zinc.