I took Jay's suggestion and started a more scientific test. I took an aluminum can, a stainless steel chain plate, and a length of PVC pipe. I coated half of each with Never Wet, and put it all in the water.
The collage picture shows the early results. Lower right with masking tape so you can see the coated and bare parts. Upper right zero weeks. Left after one week. Barnacles are apparent already At least one barnacle located on the coated part of the aluminum. The bare parts are glossy, the coated parts are matte. You may need to scroll left-right to see the whole picture.
I'll post again after a month.
![](https://lh6.googleusercontent.com/-bBDhONn1RkM/VNJHmrj56oI/AAAAAAAAXuM/DQxwwBLSJnc/s720/Never%2520Wet.jpg)
I also learned something new about my prop. Last month the diver said that he never saw such a clean prop, but he scraped it anyhow. This month, I can see the places where he scraped; stuff is growing there already.
Therefore, 4000-5000 nm of motoring did not diminish the effectiveness of the coating, but 4-5 seconds with a stiff brush or scraper will destroy it.