Originally Posted by Maine Sail
While some props are NiBrAl (nibral) most are manganese bronze. The bronze part of manganese bronze is a little misleading because most props contain upwards of 35-40% zinc.. Applying copper bottom paint can destroy them..
This prop was fine for 25 years unpainted. It was painted with a copper bottom paint and in less than one year was dezincified and destroyed.
Main Sail, thanks, great post.
Bronze has zinc in it, wow, that explains the electrolysis concerns.
Scary bunch of pictures, internal damage. I will change my ways, hope it is not to late.
You just indirectly explained why it is a good idea to have a zinc on the prop shaft. Been changing the zinc on the prop shaft every year. That probably helped a little??