The cool thing about this one is that the heroine is a U.S. Navy pilot, who has to eject from her jet into the ocean, and a few times her training is very useful. She gets to do an especially cool thing near the end.
Plot elements: heroine is stranger in a strange land; hero is ship captain. Pirates have been wronged by society, are seeking revenge, and have a code of honor. Pirates have a base on a tropical island. Heroine befriends various of the crew, who are loyal to her. The equator is crossed, with appropriate rituals. There is a perky cabin boy. There is a sea battle, with cannon. Bonus heroine crossdressing; she wears her flight suit, which is strange to her hosts.
Avi's YA novel The True Confessions of Charlotte Doyle isn't really a pirate novel, but a sea adventure. Charlotte ends up alone on a ship with an evil captain, whom she initially trusts because he is of her own social status, despite warnings from the ship's cook, an old black man. One of the best things about the book is that her opinions are very much of her time, and when her opinions change, it's fairly realistically portrayed. After she realizes the captain is evil, she sides with the crew and learns to be one of them, working the sails, etc.. When she is returned to her parents, she can't handle the restriction and refuses to forget her experiences; she is out of place in her own society, and returns to sea.
Plot elements: heroine is stranger in a strange land and also hero. Most of the sailors have a code of honor. Heroine befriends various of the crew, who are loyal to her. Bonus heroine crossdressing.
I've got a couple more pirate romances on the TBR.