I think it would be awesome if you had a map dedicated to boat battles and expand what you already have.
For starters, I think it would be cool if each kingdom could create a flagship. This ship would be massive and have lots of health. When players die in the sea battle, they will respawn in this ship. The ship can be repaired during the battle and players could choose to do those jobs (tarring cracks, fixing holes etc.) It should also have alot of guns for side-to-side flag ship battles
In case of side-to-side battles, could also introduce boarding. From any boat, you can either swing across (flagship) or use a boarding ladder and attack the crew directly.
The flag ships should only be available on pre-planned sea battles. To win, you have to either take down the enemy fleet and their flagship or take over the flag ship.
Just a start
