Here in the Florida Keys, we must have a diver clean the bottom once every 30 days. Especially the props. Barnacles love the bare metal on props.
18 months ago (the last time we were on the hard) I sprayed my clean prop with Never Wet. I didn't have much hope for it. I thought it would wear off quickly. It didn't.
Now after 18 months, the diver told me he never saw such a clean propeller before. Not a single barnacle or bit of slime. He wanted to know what I did to it.
I bought Rustoleum Never Wet at Home Depot for only $16. They call it a "super hydrophobic"coating. It is very much unlike anything I've seen in the past.
Next time we are on the hard (next summer), I'm going to use it on a test patch on my hull. If it works well, it is very much cheaper than toxic bottom paints. I'll post here two years from now about how it worked out.
A friend is also testing Never Wet inside his boat. He had been using ever more toxic chemicals to try and prevent growth of mildew, and none of them worked. We reason that Never Wet not only repels water, it should repel moisture and thus prevent mildew or mold from growing. I'll report back on that experiment in a year.