I will be honest. Current Dreadnoughts are amazing and powerful ships... however there are some issues with them that I believe should be addressed.
1. Dreadnought speed, I believe should be increased very slightly, as sometimes fights with cruisers or destroyers in a dreadnought can be frustrating and unfair when they zip in and out of render distance to snipe you, only to hide again behind the render distance.
2. Dreadnoughts should be divided into two classes; Dreadnought, and Battleship. Battleships were created to one-up the dreadnoughts of the First World War and aren't actually that much of a stretch to add. Yes, they would be bigger, more heavily armored, faster, and have much more firepower than their older cousin, however I think this can be balanced by, oddly enough, making battleships almost unfairly expensive to manufacture and decreasing their fuel efficiency drastically from dreadnoughts. The point of battleships is for them to be an almost overpowered warship, but extremely expensive to build and maintain. If all this cannot be implemented, then perhaps the armor and firepower limit for standard dreadnoughts should be increased by 10-30% to allow for the construction of ships mimicking the historical deadliness of the Imperial Japanese Yamato/Musashi or the Imperial German Bismarck/Tirpitz.
3. Even though ships have reasonable limits to the type of cannons mounted on them, I think that all warships, not just dreadnoughts, should have the ability to arm themselves with any and all cannons that can be mounted on a ship of a smaller class. This will allow ships to not only be much more versatile and interesting, it would also make ships more interesting, as cruisers and dreadnoughts in real life would often have much smaller caliber cannons mounted on them to counter destroyers or corvettes. Also... what isn't cool about having a dreadnought with 22 9-inch cannons?
4. Dreadnoughts should have the ability to carry one aircraft on them. Ships as early as 1913 would often have biplanes that were launched by catapults to counter enemy bombers. Bombers would be too overpowered on a dreadnought, so a fighter is pretty balanced. I believe the fighter should only have the range of 400 blocks that the fighter can fly around the dreadnought.
If any staff are reading this, these ideas are not meant to be implemented all together. They are four different concepts that, even if only one was added, would make naval warfare in the Nations server not only more realistic, but also more dynamic and interesting.