I agree about in gear/out of gear; I think I discovered this by measurement, but I may have mis-remembered - I'll check again next time I am there. There is a flexible coupling, but it is bridged with a wire braid - I guess I had better make sure this is clean and well-connected. The anode is more than 1m from the prop, but probably not much more. My plan now is to make sure the path from prop shaft to engine to anode is all good and connections clean. Then a paint job as mentioned before. Again thanks for the helpful responses.
