User blog comment:JAlbor/Assassin's Creed: Black Flag Q&A Opportunity/@comment-99.3.8.226-20130816153958/@comment-13471981-20130816154348

There will not; multiplayer will follow the same pattern as the previous multiplayers from Brotherhood, Revelations and ACIII. A new feature called "Game Lab" will be present, allowing you to customize match settings to some degree, but there won't be any naval battle multiplayer.