Just to be on the safe side take a digital voltmeter and put it on the resistance scale. Take a measurement between ground and your prop shaft just to verify if in fact it is bonded and and how well.
On my boat there is no prop zinc. There is a very large zinc attached to the side of the boat, around 15"x6"x1", with bolts that go through the hull
. A separate wire runs from one of the bolts to a rubbing contact on the propeller
shaft, something I always check. :-)