In Black Flags, Blue Waters author Eric Jay Dolin says pirates would rather not engage in a fight when they captured a prize ship.
The downside of a battle is the target ship might be sunk, some of the valuable cargo might be destroyed, and more significantly some of the pirates might get hurt or killed.
The far better battle strategy was to win through intimidation. There were enough accurate reports of pirates torturing or killing captives that an approaching pirate ship would create justifiable fear.
Rather than engaging in a bloody fight, the plan would be to raise the black flag when approaching the target, thus announcing that there was going to be a capture momentarily. Most ship captains would strike the colors (lower the flag meaning they surrendered), drop their sails, and prepare to be boarded.
The delicate dance of piracy at sea meant all the valuables will be turned over to the Pirates. If they perceived there were lots of goodies hidden somewhere in the ship or a passenger was hiding something then there would be beatings and tortures to produce a quick confession as to the location of the goodies.
After plundering all the wealth and useful provisions the ship, it’s crew, and passengers would be on the way only without gold, silver, gunpowder, weapons, or valuable cargo.
This reminds me of the tale of Dread Pirate Roberts in the movie Princess Bride. In that delightful tale, obviously feeding into the fake stories of piracy, Wesley, our hero, becomes the Dread Pirate Roberts becoming filthy rich by raiding ships at sea. Turns out that the title Dread Pirate Roberts is transferable. When one captain tires of raiding, he retires and transfers the title and the reputation to an understudy. The new captain takes over the title and can capture any ship he sees merely by declaring he is the Dread Pirate Roberts. The horrible reputation of DPR precedes him and ship captains can’t strike the colors fast enough.
The humorous plot line in the movie that the transferable reputation alone makes target ship surrender is entertaining. In actuality, that was the primary technique which pirate crews used to capture their targets.
When you think about it, that is actually quite a clever plan. Why risk getting yourself hurt when merely unfurling a frightening black flag might win the battle for you?