I had my 2017 2820 pulled out of the water prior to the hurricane threat. It lives in a slip on the lower Potomac River (salt water). I went down to spend the day today cleaning prior to putting her back in the water and the bottom of the tub was caked with barnacles, also,had them to a lesser degree on the sides and back of the tub. The bottom of the boat itself looked great, just a very few barnacles on the stern area. So why on the tub? Everything was painted at the same time and same paint. Is it because much of the tub is out of the water (I guess) when the boat is on plane and the tub doesn't get scrubbed clean like the bottom when under way? Or due to the aluminum under the bottom paint? Thank you...