I am painting the lower section of my bravo one.What type of primer do I use.Zinc?

I used a zinc primer. Its discontinued now but you can find a bunch of options here. The stuff I used was an alternative to zinc chromate, not as nasty for your health. Some options here:
http://www.skygeek.com/942.html

This is what comes up when I search what I used prev.
http://www.skygeek.com/a902.html
Its lasted 2 years , so its not bad.

the tempo a902 chromate free green primer at the bottem of the page is what I used. maybe it can be found somewhere.
http://www.skygeek.com/zinc-chromate.html

I used self etching primer in a spray can from a local NAPA. Krylon?. It is recomended as a primer for all metals including aluminum, has some zinc in it if I remember.

Rustoleum has a Zinc primer

Ppg Dp 90