I have to make some assumptions here, so I am assuming you are refering to your shaft zinc and bronze through hulls.
The green on the through hulls is the normal patina associated with bronze oxidation and is not a symptom corrosion
. So you are fine here. Corrosion
damaged bronze will turn pinkish and become spongy as any zinc in the casting alloy is eaten away. Most quality bronze will not readily undergo this damage.
The shaft zinc is protecting your propellor and shaft and, possibly to some extent, components of the engine/transmission. The exception is if you have your through hulls bonded to the engine
. Then the zinc will also be sacrificial for them.
I think you are fine and do not need to worry about the green through hulls.