Originally Posted by nk235
Ok so here is the update. I uploaded a picture of what the shaft looks so now that you can all see it firsthand, what do you think? Also I coudl see that the zinc on the shaft is very deteriorated and half missing so I know there is a problem some where.
My main concern is with the hose clamps on the stuffing box hose. Replace those before you do anything! Also use AWAB non-perforated hose clamps when you do so..
Beyond that clean up the stuffing box & shaft with a brass brush and some Scotch-Brite. The box and shaft should be a uniform color with no splotches of a pinkish tinge.
Contrary to popular belief many marine bronzes do contain small amounts of zinc and can show signs of dezincification.
Tobin Bronze, what most marine shafting was made from, is generally 60% copper (Cu), 39% zinc (Zn) and 1% Tin (Sn). Tobin Bronze contains rather large amounts of zinc. If you are going to see dezincification it would more than likely be on the shaft rather than the stuffing box which is most likely a real bronze with a very low zinc content..
The difference between brass and bronze is essentially Zinc content. Brass is loaded with it and Bronze, real bronze, not Manganese or Tobin, do not, in content above 15%.
The main alloys of brass are, copper and zinc. The main alloys of bronze are copper and tin. The names of said alloys can cause lots of confusion as “Manganese Bronze”, what lots of props are made from, and “Tobin Bronze”, sometimes called naval brass, are actually alloys of 60/40 brass with about 1% manganese or 1% tin added. Even this little bit if Sn puts them in the bronze category instead of brass.??
These spots are dezincification of brass. It will look similar on a Tobin Bronze prop shaft..