Should people be able to use cannons and ifv's in Scandinavia and America? No, nobody wants that and following that same logic, why is PVP allowed in naval regions, or at least PVP on a boat where the pilot cannot move and is almost guaranteed dead?
To fix this problem of PVP being able to dictate naval combat, once in dc mode after 3 minutes you gain complete invincibility but not able to do damage, only knockback, and if you get out of dc mode you will have it removed. This would make it so you can not just go into dc whenever to be invincible and if the pilot wants to fight someone on their boat, then they can get out of dc themselves and fight.
Some people may disagree with this, but currently, to combat the issue of PVP on boats, people have to make skyscraper-height towers to sit in so they are not at risk of getting mauled, and on a ship, it does not look good at all. If this suggestion made it into the game, ship-on-ship combat would be more realistic and would prevent horse gymnastics.