Kinda sad that a free roaming assassin game makes a better ship combat part than dedicated ship sims or pirate games have done so far.
And even I have to agree, the ship combat in AC3 was absolutely visceral and stunning. The sounds, the feeling, it was there. That is how I think (slightly unrealistic, but epic) ship combat can work in a game and be fun, if you just add a (proper) upgrade element, free roam and questing. It doesn't even need to during the 1800's .. basically any sufficiently armed and fast ship could work. Like PT Boats (You could make a great Fallout style scavenge game just cruising around finding stuff doing quests.. think Fallout on the Ocean)