I think this is from vanilla, but i've found when you have a few support ships with just a few melee/missile ships, beating almost any other navy out there is almost guaranteed... As long as you auto resolve. Especially when it's an army on transport ships. But when you fight the battle manually, it's likely you'll have your ass kicked.

I'm a bit disappointed in myself for taking advantage of this, but it's the only way i've kept Rome from being completely overrun by 3 big empires. They're just constantly sending stacks at me from the sea (seleucids, Sparta, Egypt, now Persia).

Never really liked how armies can just magically have a fleet once they hit the ocean. Is this something not easily changed?