Aquamet shafting

[Santa Cruizer]

It seems there is a marked difference in electrolysis characteristics between Stainless and Aquamet shafts.
My bronze propeller has completely deteriorated in less than three years even though the new shaft has had multiple zincs attached and regular inspections/replacements.
I am wondering if anybody else has had this occur.
I am thinking that a propeller zinc at the tip of the nut might be the answer. In any case this is a problem that need a solution.
Even considering the normal stray currents that occur in the slip I am in this is an amazing amount of deterioration.
Does anybody have any thoughts?

[Ken Juul]

Not familiar with Aquamet.  Might want to ask the folks that make it.  www.aquamet.com

the zincs should be softer than the brass in the prop so they should go first.  If they remain and the prop dissolves, they obviously aren't making good electrical contact with the shaft.  Perhaps there is a coating that needs to be removed to allow good contact.  Or maybe the slightly more expensive zincs with the steel BB need to be used to make good contact.  Have friends with the small prop mounted zincs.  They hate them, need replacing about every other month.

It is probably just as important to find the source of the electricity causing the problem.  Not sure how to advise.  Think it has been discussed here before.  Perhaps search on electrolysis.

[scotty]

Also check with neighbors about their zinc logevity.  There may be stray current in your location (a "hot" harbor).

[Ron Hill]

SANTA : Not too sure which shaft Zn you use. To make sure there is good contact, and buy the ones that have a "BB" on the inside.  Then whack the shaft Zn with a hammer, rotate the shaft and whack it again, then tighten the Zn.  I do that whack and rotate a couple of times.

A few thoughts