The El Impoluto
To reach the Legendary ship, the El Impoluto, you will need to defeat the fort located in the northwest of the map called the Dry Tortuga Fort. Once you have taken it over, the legendary ship will appear. The Impoluto is a mean ship that likes to take its path directly into the side of your ship. Its main maneuver is to ram you, and when it does, it does devastating damage.
You’ll always want to keep out of its path and try to stay away from its side cannons as well as it fires an enormous barrage of cannonballs at you in one go. When the behemoth begins to charge you, your best bet it to turn away from it, the opposite direct that you are traveling instead of trying to out run it and letting it pass. If you let it pass, it will swing to the side and unleash on you. If you turn away from it, you will be able to fire a volley into its side and then continue forward to come up behind it.
Once you get behind it, you’ll want to stay there and then unleash chain-shots into it. Once it gets slowed, drop mortars on it and more chain-shots, and front cannons. This is a way to attack most of the legendary ships, but it is highly effective on the Impoluto as you are safe from its ram once you are behind it. Stay there and unleash on it all you can, chipping away and ramming it when you can and the beast will sink soon enough.