i want to paint my galvanized jon boat trailor....how do i go about doing this? what paint? what primer?

I'd go ask a real pro at your paint dealer.

I have done this on my jon boat's 1967 rusted out trailer. At home depot or Lowes or any home improvement store their is a spray on primer which you can even apply to light rust. First scrape it down and take the old paint off or rust. Then dissassembale all the nuts and bolts and paint each piece seperately. I would go with Rust-o-leum paint they have nice colors are tottaly outdoor proof and have a great price. I would also buy some outdoor gloss finish to look cool but the paint that i said to buy has glossy paint. Do not use an aerosol can use the good ol brush.

Try to GOOGLE "InterLux"  an antifouling primer and paint.  I have it on a reconditioned 1982 Sea Nymph and trailer.  It drys hard, shiney and cleans up very well but its a little pricey too. ;D

Go to your local Lowes and pick up some Valspar Primer and Paint. You won't be sorry for that purchase and neither will your boat trailer.

JT Bagwell