The prop is a Martec Autostream. I dove the boat a week before the haul-out and found the prop zinc was totally consumed. It had only been about 4 months. Put the new one on and a new shaft zinc as well. After a week both new zincs were pitted. Also found that the pitch adjusting screws and nuts were damaged on the parts exposed to the water. Did not see any damage on the prop itself but the strut showed some copper. When we got back into the slip I checked the grounding and found 42 milliamps DC and 4.3 milliamps AC through the ground wire. Open circuit was 0.24 vdc and 0.047 vac. It did not matter if the shore power breaker was on or off. Put in a Yandina Zinc Saver and both readings dropped to 0. Hope this solves the problem.