For a game supposedly about war and the crafting of warthings, World of Warcraft [official site] doesn't have much of any of that. Mostly the Horde and Alliance stand on opposite sides of the warhall sneering and occasionally yelling e.g. "You're rubbish you are!" The Warlords of Draenor expansion did add a little warcrafting, though, letting folks build and upgrade their own garrison.
Now Blizzard are expanding that to include warboatcrafting, rolling out shipyards. You won't sail them around engaging in actual war, of course, but at least you can feel comfortable that you totally could and would if those cowards would dare come round your manor.
Shipyards let garrison owners build ships to send out on missions, which sounds like floating Followers basically. That's less exciting than one might hope. Blueprints in the game suggest you'll get to build destroyers, submarines, and other naval units that got on my tits in ye olde non-World-of Warcrafts. Building a shipyard will also open up access to 6.2's new zone, the Tanaan Jungle.
Shipyards arrived on the test realms in patch 6.2, and will sail away to the four corners of the warglobe after testing wraps up. The patch adds a new raid and loads of other things too, so do hit the patch notes if you want to know it all.