Outside of combat and trading, there's a core gameplay element that seems to be missing from this game, to make it fully engaging and more sim-like.
My main gripe with Naval Action is not its slow pace, nor its detailed trade system. And certainly not its tension-filled sea combat.
Rather it is in the feeling of grinding for XP that this game conveys, a game design sin typical of MMORPGs. To be sure, this feeling of grinding for XP is the single biggest reason for my install/play-a-few-sessions/uninstall relationship I've had with this game over the last two years.