When a ship is standing freely and an enemy ship appears within range of its unit, it will be automatically fired upon. When we order our ship to attack an enemy ship, it will approach and attack until it or the other ship is sunk, unless we cancel the order and order the ship to retreat.
When the ship loses the amount of HP that the sail adds to it (see link below), it is broken and the ship cannot move. It must be towed away, but it can shoot when it is within range of the attack.
Ship Parts Prices and Statistics
When a ship is destroyed, the goods that the ship carries (those in slots) fall out in a certain percentage (some of the goods are simply destroyed) and drift on the sea in the form of crates. After some time, if they are not picked up, the crates sink and the goods are lost.