I would advise you to check your anodes ( if you can see them ) !!!!
Moved Marichelle to another berth on F pontoon Sunday as it is getting too shallow where she was, as there are no plans to dredge that part of "F Pontoon" in the near future.
Replaced anodes in April of this year, noticed in August that prop anode nearly gone when I was scrubbing her bum in shallow water, rechecked sunday only to find the 1kg disc anode was 90% eroded away !!
This has never happened in the 10 years I have been on that berth, I have heard through the grapevine that there have been quite a few occasions of this occuring in the marina this year, and an expert has been called in but nothing conclusive has been found..........but there is obviously a problem somewhere ??
Just a bit of advice really, hope it helps .