Originally Posted by PaulinVictoria
I am assuming cleaning the hull would also remove the expensive paint much faster than just leaving it there, requiring re-coating with expensive paint more often. In which case, what would the expensive paint manufacturers have to gain by suggesting that it never gets cleaned (or cleaned less often)?
I don't expect that you would have any experience in this, boating in a region of very low fouling as you do, where hull cleaning is rarely (if ever) performed, but frequent, gentle in-water hull cleaning actually helps an anti fouling paint last much longer than it otherwise would. In regions of moderate to high fouling (such as California) anti fouling paint is going to foul fairly rapidly. Allowing it to become even moderately foul means it is then necessary to use abrasive cleaning media to remove that fouling. This (of course) scrubs paint (and therefore copper) off the hull and into the water. By cleaning frequently, the hull never gets particularly foul and the softest, least abrasive cleaning media can be used to remove fouling growth. This keeps the paint (and copper) on the hull, where it belongs.
The paint companies are up against the wall. They were able to recently defeat proposed legislation (similar to Washington's) that would have banned copper-based anti fouling paints in California. They have much to gain by making their products appear to be less polluting and in-water hull cleaning to be more polluting.