The twins are pretty much the toughest Legendary ships that you will come across out of the group. It’s not so much that they are that powerful, it’s that you will need to face off against both of them at once. When the battle starts, they will come at you and try to get you go in between them. Try to go around them and make sure you never get caught between the two of them. They will obliterate you with their broadside cannons, hitting you with both ships at once.
You will want to use your mortars from a distance on these two and hit whichever ship you have a shot on. Don’t bother going after just one of them for now and make sure you never stop moving. Hit both when you can and try to keep your distance. Once you get one of the ships down to very low health, leave it alone and go after the other ship. Once both ships are down to very low health, sink one and get ready to run.
It may sound silly, but when one ship sinks, the other with come after you with a vengeance. It will try to ram you using incredible speed, so once the one ship is down, sail away from the other as fast as you can, launching mortars and fire barrels behind you to hit it as it approaches. Make sure to hit it before it gets to close as it really will gain on you in no time even if you are going as fast as you can. If you can hit it while it’s charging you, you should sink it--and feel free to breathe a sigh of relief.