Galvanic Isolator on 35CB

[Rondo]

We have had our 2007 CB for about a year and a half. She went in for a bottom job, first thing after purchase. The first set of zincs lasted just under a year, which I consider pretty good. My diver just let me know that we need new zincs next month, meaning they lasted 5 months. We keep her behind the house in the canal, here on the Florida West coast. Don't know what changed, except one of the neighbors perhaps has something new going on. We have not made significant changes to anything electrical, except a new set of batteries. I am just about to open up the rod holder panel that also houses the pair of 30 amp shore power connections to see if there might be a galvanic isolator installed. If not, I will install one post haste. My testing, thus far has not shown any suspects to cause this change.
Can anyone say if the boat had an isolator installed at the factory? A manual for most things was on the boat, but no isolator info, so assuming there likely is not one. This is not a particularly daunting task, just curious.
Thanks for any ideas.
Rondo