A few ideas on possible changes for people to consider.
First: have three different types of ships as we have now; skiffs, frigates, and galleons. Each ship has a stat arbitrarily called SHip Power. A player can acquire any of these whenever. However, each type behaves differently. Skiffs are small and fast and are glass cannons. They would distribute their SHP with 2/3 of it going to attack and 1/3 going to defense. Frigates are balanced ships with SHP being divided 50/50 between the attack and defense. Galleons would be large and strong with 1/3 SHP going to attack and 2/3 to defense.
As to buying the ship, a player can buy any type of ship and any level up to his maximum. The max level is determined by the player's level (or nautical level or average of the two, whatever). The cost of the ship is determined by the level of the ship.
Second idea: Raising ship level. Ships could have their level raised at a Shipwright NPC. It would cost so much gold per level to level the ship. I would also like to see a currency (lets call it upgrade materials for the sake of this post) that is also needed to level the ship. This could be treated like gold or practice points or be no-trade items. I would suggest the number of upgrade materials needed increase the more times that particular ship is boosted. So the first level the ship is given takes gold and one "upgrade material." The second level would cost gold and two "materials." This would make a level 50 raft very rare and a real accomplishment. These upgrade materials could be quest rewards and/or crown shop items.
Third idea: I think ship equipment should be changed to boost stats by a percentage instead of a flat number. A percentage increase would allow the same equipment to be viable on a ship without being subject to depreciation due to a ship's stats increasing with level.
I have lots of other ideas which I think would be neat to see implemented, but I would like to see what comes of these ideas first. I would love to see some feedback on these ideas! Thanks all.