If you notice, Look at the block size between ships, None of them overlap each other, so you can either have one or another, one ship cannot be 2 types of ship. Unless its very specific on its blocks the main way to split them apart is by size.

If we want to consider adding new ships we will have to rework the limits and maximums of blocks on ships, for as gods said we cannot have ships overlapping each other.

If we make ship max’s bigger and limits bigger, this allows us to make new ships bigger then before for the new players, so that they can have decent sized ships instead of driving rafts. Also, if we do that, it wouldn’t upset the power between old ranks getting bigger ships, because all ships would generally become larger.

Another road is to make new ranks, and make new ship types to be associated with different ranks, however, this would simply make more to attain in the game, higher rank=better ship/bigger ship, which will upset new players because they have to wait longer to get some decent ships.

So there are some points to consider when adding new ship types, and I think we should choose which we would rather do, increase ship max’s and make new ship types to fill in the gaps, hereby making all ships larger for all players, or simply adding more ranks to the top.

Also for ship types, scroll down the wiki until you get to ships where it names real life classes of ships and description of them.

http://europe1600s.wikispaces.com/Pirates+%26+Sailors