Windward is a fast-paced naval combat game set in the fantasy time period similar to the mid-17th century. It features a variety of different ships to choose from, different maps to play on, randomly generated booty to discover, talents to earn, ships to unlock, and plenty more. Play skirmish by yourself or with up to 15 of your friends and become a feared pirate like no other. Best of all, you can try it for free!
I just played the web demo, but it was quite a lot of fun. Very visually appealing, and looks like it has a lot of replayability due to customization.