There is a ship-seller on the island called Dragon Cove (on the upper left-hand side). It's called Ship Shape, and once you save enough doubloons to buy a ship (from trading items - see guide) you can buy another ship.
(Answer provided by Little Bird)
Go to the Chinese island and go to the ship yard. Talk to the second guy.
Just dock in an island and your ship (or raft) will fully heal.
You go into any harbor.
The cannons on your ship!
No. To sail a ship, go to Skullduggery Island.
You can trade your ship in when you buy a larger one.
you have to get doubloons by trading grain silk medicine and spice (go around all of the islands on skullduggery)
You repair your ship by pulling into any harbor. You can upgrade your ship at the ship builder's at Dragon Cove.
you dive to were your ship(raft)is and you swim till you get to sand
Once you've gotten to the Japanese island you go to the guy selling ships and if you have enough money you can buy a bigger ship.
The only ship you go on is your own. You begin with the raft and you buy larger ships as you can afford them.
When you have enough doubloons, from salvage or trade, you can buy a larger ship at the Shipbuilder on Dragon Cove.