Everyone seems to gravitate towards frigates and battleships-land bombardment and city capture seems be the prime motivator since sea battles aren't really happening.
What's so awful about the niter req? If coastal players could spam frigates it would be an absolute madhouse. Although the pinch with muskets and bombards at the same time really hurts.
The later game ships don't seem balanced to me
at all. But hardly anyone uses them in naval combat. For example, the resourceless Nuke Sub is 85

/80

, where a missile cruiser is 85

/70

, and a destroyer is 80

. Destroyers have no attack bonus against subs, they can just see them. Why do nuke subs (the counter to naval ranged due to stealthy) have so much defense? Destroyers would beat missile cruisers without a screen as well, and nuke subs would also beat destroyers. It's all quite confusing.
In general the caravel, ironclad, and destroyer are a little weaker than contemporary land units, which probably really hurts them in the city attack dept as well.
That's probably because there are only two early naval units for the first 3 eras of the game: Barbarian Quads churned endlessly out of the barbarian
starforge camps, and our poor galleys that stand no chance... How I miss the galleass!