You will have 5 main types of ships to choose. Well... 6 in fact.
They differ in 5 values: speed, size of cargo hold, number of cabins, and count of sailors and guns.
No worries, all of the ships are quite universal. In the worst case scenario you may sell one ship and buy another one! Moreover - you may command even two different ships at the same time!
You begin the game with Cutter - Sloop class. Cheap and small, general purpose boat, with relatively good speed.
There are two specialised cargo ships available:
Caravel - smaller and cheaper one, with 2 cargo holds, and...
Galleon, which has 3 of them, and is significantly heavier armed. Both are the same slow. You should consider buying one of them, when you have a plantation or mine, regularly providing some amounts of cargo, which has to be transported.
If instead, you decided to explore new lands, Brig seems to be a better choice, as it is very fast. Not very suitable for carrying the cargo however.
Frigate is bigger and better armed than Brig, however, usually a bit slower as well.
There is also a Battleship present in the game. One player only can have it. It is enormously big, full of guns and soldiers. Undoubtedly real dominator of the seas.
In the game, just like in the reality, there are some general rules in place:
1. Ships with bigger cargo holds are slower than good looking ones with low profile-hull;
2. Heavy armed ships have almost no place for cargo, but still they are ... quite heavy;