Painting Bottom and protective coating

[RunningBear]

I have a 1971 Grumman 14' Semi V Hull aluminum of course, what I need to know is what can I use and not expensive to paint the bottom it and put a outer layer of protection. This boat had lot of oxidation to the hull and had to put on this stuff call Lab-Metal on it to make the holes sealed. That can wasn't cheap and I'm on disability now and can afford much and can't work like I did before I became disable! So anyone have any ideas would great appreciated?

 

[Chris1956]

Two questions: Do you keep the boat in the water or trailer it? Do you boat in saltwater or freshwater?