In March I hauled out and sprayed the propeller with galvanizing paint.
To cut a long story short. It didn't work.
It is about as effective as nothing.

It was an experiment, because where I am is a very productive aquaculture area.
Oysters. mussels, scallops and a variety of edible seaweed thrive.
All of the boats get about 8 months from professional prop coating.
I have a feeling that the antifouling and prop coatings are environmentally benign to protect the crops.
In other words. not very effective.

So I gave gal paint a try.

Oh well it was worth a try.
gary

Give lanolin grease a try. It should be environmentally safe. I used it years ago on my fishing vessel. I've tried all the weird stuff! Strip the prop back and polish it. Heat the propeller so it's too hot to touch and slop on the lanolin grease. Use a flat stick and give it as much as it takes.