This idea seems really cool. But there are some things I would like to add:
Alright, lets say starting from the classical age, players have the ability to upgrade their dock into a naval port. By doing this players are given access to 3 different types of ships (Names aren't final as I don't know all the types of ships). These ships can be deployed in offense or defense.
- Offense Ship: Like stated int the initial post, this ship will target a location and barrage it every 30 sec, kinda like the barrage tactic. It does a good chunk of damage to buildings/defenses and moderate damage against ships. When placed in defense, if the ship successfully destroys the other ship in offense, it will periodically barrage the attackers troops every minute or so
- Defense Ship: This type of ship specializes in taking out other ships. Thus its most likely to be placed in defense(Similarly to how generals are deployed in offense/defense). In offense this ship will prioritize ships before eventually attacking defense buildings, whereas in defense it attack other ships before barraging the attacking troops. The main weakness of this ship is that it does almost insignificant damage to defense buildings/attacking troops.
- Transport Ship: This ship periodically transport troops to the battle. No matter whether its placed on offense or defense it will deployed a small squadron of troops that increase is number and tech level as you level up the ships. However, it does no damage to other troops and thus is a sitting duck to other ships. So its best to use this ship in conjunction with other ships.
As you upgrade your naval port the number of ships that can be deployed increases (ie. classical age is 1, medieval is 2, gunpowder is 3 etc.). In order to upgrade your ships you use the blacksmith. What do you guys think of this. None of this is final but its an idea I want to throw out