The Ship
The Ship is used for exploring the World Map and transporting loot from the World Map locations to the Home Island. Initially, the Shipyard has to be repaired, which then allows the player to repair the Ship as well. It can then be fueled with Diesel, and crewed by sailors, who are just workers. As you keep upgrading the ship, it will keep increasing the number of required sailors.
Ship Upgrades
Overview
Parts of the ship can be upgraded. These upgrades increase the ships battle score, and exploration capabilities. In addition, the ship's appearance will change as upgrades are added.
Weapons and Armor
Mainly improve the battle score. You can add two instances of each.
Bridge
Increases the radar discovery range of the ship. This allows you to see further areas, and what they contain, although not the loot they have.
Also increases the battle score.
Engines
Increase the ship's movement speed and fuel capacity.
Fuel tanks
Increases the ship's fuel capacity.