More likely bronze than brass.

DP
wrote in message
...
Unlikely it dissolved off due to electrolysis.
Most likely you did not put it on correctly?
Put another on and dive on it once a week.
Brass prop shaft - I have never seen one - only SS.

stu



"Rob" wrote in message
om...
I have a Catalina 30 with an inboard diesel that I launched in May of
this yr- this weekend while swimming off the back of the boat I took a
swim below with a mask to check out the bottom. I noticed the zinc I
just put on the brass prop shaft 3 months ago was missing. I put it
on myself and remember how tight I made the screws- is it possible for
it to either fall off from vibration or deteriorate that fast? The
rudder zinc is still there. I keep my boat at a private dock in a
creek- the closest boat to mine is about 100 yards away. I have shore
power- is the AC ground possibly doing something to speed up the
galvanic process? Any ideas on how to replace the zinc without
shelling out for a short haul?

Thanks-
Rob