I had an aluminum
boat for ten year, sold her in 85. I hauled her twice - once in Hawaii
where ther are virtually no tides, and once when I sold her. Other than that I always careened to scrub her bottom. I painted in those days, too, but you can no longer do that, nor can you sand. Scrubbing, however, is okay. But do not do this with a fin keel
or the so called 3/4 keel. the boat I am building now has a full keel and I will careen to scrub her. Find a nice soft beach, and if you are nervous about it, lay her down on a tire at the bilge
. It is easy and fun to do. I once had my schooner careened in Port Townsend before they moved the ferry dock
. I was sitting on the sprit waiting for the last of the tide so I could scrub and a car load screeched to a stop at the road above me. They wanted to know if I was aboard when it happened. Then if they could help. I told them to come back in half an hour with some scrub brushes
. They drove off in a huff.