A two part linear paint will last the best and has great durability to scrapes and scratches. I painted one of my old boats with awlgrip. I couldn't get the hang of learning
to use a sprayer (drip city!!), so I prepped the boat out including fairing and primering it. Then I hired a car painting dude to apply the paint, I had everything ready for him when he arrived, (scaffolding, paint, everything). Way cheaper that way as most of the cost of a paint job is in the labor to prep the surface. Plus you know the surface was prepped right.
degrease before you begin to sand the old surface (voice of experience).