Paint

Hello,
I heard everything about the merits of POR15, but it got me thinking...If road salt is the biggest offender, why no one uses paint for marine applications?
It should be made to deal with the most extreme elements: salt water (did I mentioned this one already...?) and friction (the friction between water and paint should be higher than between paint and air...I might be wrong)
So, if my assumptions are correct, why would one spend extra hard earned $'s on POR 15, when you can buy tons of cans of boat paint for the same money?
Where did I miss the boat (pun intended)?
Boris

POR stands for paint over rust.
You cannot paint over rust with boat paint. The rust needs to be removed and the surface repaired before painting. W/ por, you do just that, paint over the rust. One step.

I've tried a couple of different marine primers in the past, including zinc chromate and red lead. It seemed like a good idea, but it didn't work much better than regular paint, and not as well as the original fish-oil based Rustoleum rusty metal primer.