I will share the secret of a succesful ship. It is about grinding, grind a lot on drills and you can get to have an unsinkable fortress. Try out some designs you made and see which is the best. Make sure it has some armor! now get all your guns and stuff and put it on your ship. Grind duels 1-4 and get enough money for a 30.5cm gun. Now grind 5-6 and get more of these guns. When you get 3 or a 40cm gun go higher up the duel list to about7-9. Get a 46cm gun (watch out! this gun is HUGE 8*8*3 make sure you have space or make a new ship) now grind further up and be sure to get all stars to improve shooting accuracy. TIP:shooting drills arent hard and can earn you extra stars and money so do them as well.