Butch33,
I recently took my freshwater pontoon for a weekend in brackish water near Eglin Air Force Base in NW Florida. I launched and kept the boat at a slip at the Eglin Recreation facility. They rent pontoon and other boats there. On a lot next door there were several of their retired aluminum pontoon boats. All were covered in heavy layers of barnacles. I spoke with the manager there and he said he had not found anyone willing and able to remove the barnacles, so the boats were effectively a total loss. ... So I agree with those who told you that barnacles are a problem best prevented rather than corrected after they appear. On my fiberglass sailboat, I used a copper infused (poisonous to barnacles) ablative paint that intentionally sloughed off over a couple years to take whatever barnacles that attached with it. It had to be reapplied regularly to remain effective. I don't know what paint is used on aluminum boats.
