How much do you want/need to remove? If you are going to repaint (best option) I would not remove all of it. A light sanding and a wash with denatured alcohol will remove oxidation and be a good prep for the new paint. Otherwise a chemical stripper will work, but you are going to be scrapping and scrubbing a very long time. Tight places around trim are going to be extremely tough and will require steel wool and small almost dental type tools. New paint goes a long way, protects aluminum from pitting, antifouling bottom paint helps performance. I would just do a good prep and repaint.