User blog comment:JAlbor/Assassin's Creed: Black Flag Q&A Opportunity/@comment-81.207.149.152-20130809203730/@comment-5546424-20130810155515

I think I read an online interview were Ash confirms that...I forgot the link, though.

However, if you watch the 13-minute gameplay video, you can hear ambient music playing while Edward sails his ship. The music also changes to fit certain situations (i.e. when you get into a battle with another ship, and you sail through a storm).