A damaged boat was the one the king did not take.
The first hidden reason
Allah showed Al-Khidr the hidden reasons. A king who was one of the oppressors seized every good boat by force. Making it look faulty meant its poor owners who had nothing else could benefit from it. It was also said they were orphans.
You did not get the bigger flat, the flashier job, the car you wanted. Years later you see what that bigger thing would have cost you. A small dent can keep the whole boat safe.
Every setback is just a loss.
Some damage is protection I cannot see yet.
Recall one past disappointment that later turned out to protect you, and thank Allah for it.