phosphoric acid is handy in polishing aluminum boats. To keep them shiny requires careful sanding with progressively finer sandpaper and is incredibly time consuming. Once it's right, it's not so bad to keep it that way but still requires regular work. I would never even consider doing it because of the time and effort spent. I'd rather spend that time fishing or annoying the children and wife, or both at once. BTW, any kind of dents or dings will show up big time on a mirror polished boat.
JMO,
JBJ