I have been playing since the beta and I think that the game could be improved with more ship types. Therefore I have a few suggestions, which still need to be worked out:
Warships: more cannons than other ships, maybe even at the front of the ship. More cannonballs and things like that at the spawn. For the galleon, cannons on the upper 2 floors.
Merchant ships: much faster in the wind than warships, armed but not as strong and can withstand more damage than other ships. In addition to harpoons, net cannons to get several chests or skulls or similar on board.
Scout ships: Least armed but by far the fastest and most manoeuvrable. But not so stable.
Ghost ships: Special ability that they sail faster against the wind. The rest could be similar to warships.
All these proposals are additionally subdivided into the already existing sizes.
I am sorry for typing errors.