I asked the marina guy to take a look at it this winter but he hasn’t yet. Anybody have a solution for this? would installing an isolator fix it? Seems like I would still need a larger zinc.
You asked. I qualify as Anybody.
You are saying basically that I have to become an expert, and doing what most boat owners do, put a new zinc on every year, is “guessing” and stupid.
I did say without information about your boat, the replacing of zincs is guessing. I know because I did that. Yes it is done every day by many owners. It does not make it less guessing. Only that the guessing may have been successful if their boats prop/shaft are still usable.
I never would insult you by using the word "STUPID". That is not relevant, nor how I would talk to any boat owner.
NO you do not have to become an expert. If you want to be a more knowledgable boat owner that likes to DIY, then the suggestion was provided as an aid.
But I am an average boat owner not a metallurgical engineer. I don’t have these skills.
This is a 3-4 skill level project for the average DIY boat owner. No special academic knowledge needed. Just the right piece of equipment and the guide to understanding the readings you see on the equipment. (provided in the package) If you can operate your cell phone or read a Digital Volt Meter you can identify the electric potential of your boat. From that, if the electrical charge that is eating your zincs is coming from your boat. Further if so, which of your systems may be causing the problem.
That leads to answering your second question... "would installing an isolator fix it?". No one can answer that unless they check your boat to see if your boat has a problem.
I would not be able to interpret the readings and know whether they are in range for the various metals involved.
I do not have an advanced degree in Electrical nor Metallurgical Engineering. I can read the DVM and then compare the information to a chart which identifies metal being affected. If chart says it is zinc then there is Electrolysis corrosion occurring from my boat. For me that indicates I should be changing my zincs perhaps 3 times a year and looking for the cause. That may include getting a Marine Electrical Engineer (expert) to help.
For most people the question is what can I do myself, and when do I have to go to an expert?
That is a question you have to resolve. If the information here is not helping for whatever reason, then seeking an expert makes a lot of sense, to me.
I hope you have a nice day.