Adding external zinc

Oct 2, 2008
3,811
Pearson/ 530 Strafford, NH
So are there any studies that prove the fish electrons go to the prop and not to a seacock or something else?

All U Get
 

JamesG161

SBO Weather and Forecasting Forum Jim & John
Feb 14, 2014
7,757
Hunter 430 Waveland, MS
I have a drop Zinc shaped like a fish.;)
Just kidding.

The drop Zinc electrons flow all over, but are used faster by the paths of least resistances and greatest potentials [Noble series].

Bronze seacocks have low potential. I have tested mine with a AgCl reference probe and show -459 mVolts where my Bronze Prop/SS shaft combo shows -950 mVolt, so the prop gets most electron flow.
Jim...
 
Oct 2, 2008
3,811
Pearson/ 530 Strafford, NH
Dropping a zinc over the side won’t get it closer than 4 or 5 feet to the prop. How would this be closer than the zinc on the shaft? I just think it erodes away to make you feel good about doing something.

All U Get
 

JamesG161

SBO Weather and Forecasting Forum Jim & John
Feb 14, 2014
7,757
Hunter 430 Waveland, MS
I have tested my Fish shaped Drop Zinc and the shaft Zinc with a AgCl reference probe.
There is a very noticeable change [improvement] in Potential with both in the water.

Both with and without the Drop Zinc were acceptable protection.;)

You might think of it, as the surface area of what you are trying to protect.

Example: Your bronze propeller has, lets say, 2 square feet of surface to corrode.
The electron flow is from Zinc to Prop instead of Prop to Shaft. We want the Zinc to provide the galvanic battery a flow of electrons, not the Bronze prop.
If your prop Zinc has 4 sq inches and your Drop Zinc 40 sq inch, but 4 feet away, both Zincs will provide protection.
It is a matter of discharge RATE from each. Not either or, but both.

Yes, the drop Zinc will reduce the Prop Zinc RATE of sacrifice. How much? :rolleyes:
Jim...

PS: The steel hulls in USNavy has so much surface area that a Zinc would not work.