Ok, I downloaded this app for my iPad (available on the iPhone too), you can design your own ship from scratch or buy a preset one. You have to balance out size, speed, weight, armament and other factors like a real battleship. And fight against AI or people online for more gold for better weapons. I found myself sleeping at 2am building my own ship.
Oh and it's FREE!
I don't have a pic of the ship I built on me right now, but here's an example of what you can build with it.