(playing as rome) I completely avoid naval battles. they are total crap.
The AI simply has too much control over their entire force simultaneously. In the time it takes me to organize a ramming run on a target or set up my maneuvers, the AI already has his entire fleet organized and attacking.
the ramming is the worst part for me. The AI ALWAYS wins unless i get an instant kill. a full speed trireme vs. a barbarian transport ship should go very badly for the transport, but if i am off center even a little bit the AI has a chance to bounce itself off me from 3 feet 2 or 3 times and my guys jump ship
at this point 2:1 is what i need just to win and keep enough alive to take a town
i probably just suck, but i have never lost a land battle (even when outmatched) and I was fine at empire/napoleon/shogun2 naval battles. it is just the ramming that kills it for me. should be a special ability or something
Using the super unit skill helps out a lot in naval battles. Having 1000 archers fire on a ship kills the enemies quickly.