You may think your steampunk death star is the ultimate weapon in the game, but unfortunately you are wrong, there is only one ship required and it is so basic that many people overlook it. The ship I'm talking about is floating gunboats. A ship equipped with twenty cannons may be powerful, but most have to include external balloons making them venerable to returning fire, or cost a small fortune to build. A gunboat on the other hand usually has one powerful weapon (A rocket is probably the best) Use sails and potentially balloons to reduce costs (Or engines for higher durability) And lightly Armour it. Then all you need is to build of these and you are set for domination.