Which marina is it. I would talk to Fisheries Supply and find out how they work in the NORTHWEST

There are so many things that effect cathodic protection on a sail boat. I'll list a few.
1. Water velocity. Fast moving current requires much more weight/surface area than still water.
2. Boat usage. A boat that is used a lot requires more cathodic protection that a boat that is used little.
3. Conductivity of water. As the conductivity increases, the possibility of corrosion increases. Salt water is more conductive that fresh water.

Theses above are just a few of the factors that determine corrosion potential.

What can help also protect your boat is a fail safe galvanic isolator. Catalina has been putting them on boats for a while. I have one on my 2003. It isn't fail safe but it's better that not having one. If you do install a galvanic isolator, it needs checked annually.

A complete corrosion survey is the ultimate way to go but that isn't cheap.

I am somewhat suspicious of this environmentally friendly thing. You need Mil Spec metal to get you the best protection for your boat and Mil Spec is pretty pure metal. Maybe they mean the anodes were manufactured in an environmentally friendly way?

David

Maine Sail has made the point in other forums that galvanic isolators do usually not have any indicators that they have failed. Simply 'cuz the way they're built - there's no "I'm not working anymore" light. IIRC, some newer ones do have that kind of feature. So be aware.

On the market today there are fail safe galvanic isolators. If they get hit by lighting they will maintain the ground connection between your boat and shore power. But not unlike many things in life it needs to be checked once a year. The check is simple and all is needed is a simple diode test function on a DVM. Whether they have an indicator or not is not important. It still needs checked at least once a year.