I’d also like to see upgrades and some renaming.
In previous Age of games, you could upgrade ships lines, however in AoE3 it doesn’t happen (with the exception of a couple of Imp upgrades for Frigate and Monitor that don’t change appearance).
Caravel
Caravels got replaced pretty quickly in the timeline (they were there just to the end of the 16th century before being outclassed - incidentally it was the Galleon that was the true replacement). The models in-game are also Carracks…
If there were no Fed States, the obvious upgrade would have been a Sloop, however they seem tide to that civ group (which is really annoying as they were used by all Euros way before…) - so maybe a Schooner or Cutter may be a nice upgrade in the later ages? These ships would feel for more in sync with Frigates and Monitors on an aesthetic level.
Galleon
These are kinda fine as is, especially as they have a utility use. Would be nice for a Royal Guard version for the Spanish. On a historic level they do get obsolete before the end of the timeline. A possible upgrade could be to Brig.
Frigate
Before Battleships appear in AoE3, these were pretty much regarded as such (even gaining a Ship-of-the-line upgrade - which is incorrect), however they were used for escorts, chasing and scouting.
I’d love to see an upgrade progression for them to be Frigate - (Industrial) Great Frigate - (Imperial) Armoured Frigate. The last one changes it to a steam powered, ironclad Frigate.
Monitor
First off, get rid of the hideous name. It’s a weird leftover from some bad Ensemble Studios naming.
Call it a Bomb Ketch. Imperial Upgrade changes it to Bomb Vessel.
Rowboat
I’d love to see the campaign rowboat in, but that’s a rather wishlisty thing!