Inside or outside of boat?
I redid the interior on my tin last year and used a couple cans of spray on rustoleum (similar to tremclad). Used the Rustoleum because it had a bit of texture. Will see how it holds up this year.
Exterior I haven't done but you could try the spray on automotive paints or Tremclad. Bit softer paint than the "official" boat paints, but a lot cheaper. Also prep is easier, I think I just did a TSP wash and light sanding. The good stuff requires chemical cleaning and etching of the aluminium.
I did some Google searches last year and came up with a number of forums with the people talking about using the tremclad/rustoleum spray cans to paint their cars. Some 'interesting' designs. Try a search.