Subject

You have found a "hot" slip, usually a neighboring boat has an
electrical boat.

Option 1:

Move back if possible, if not some place else.

Option 2:

If you can't move, if you have shore power connected, disconnect it.

IOW, do as much as possible to electrically isolate yourself from your
environment as possible.

Temporialy, you can add some zincs, but you need to address this issue
with the marina, and quickly.

You are dealing with ground currents and cathodic protection, a place
where the faint of heart should not go.

Trying to be a ground current sleuth is difficult at best. I would not
waste my time, since it is only going to cost more money and may not
be successful.

Good luck.

Lew