Building a new boat
 

I lost my first two boats through target fixation. (My Fault). Now I have constructed all needed items for a 2A; however, I cannot build it because it says I need a flak gun. When I go to purchase a flak gun with prestige points the only button open is the cancel. I can not complete the purchase. It will allow me to purchase with geld. I don't have enough. It looks as if the flak gun is not available. How do I get this flak gun, short of paying geld for it? Do I need to level up to gain the technology? Please advise as to how I can do this.
Thank you,

I could be mistaken, but I believe that the 2cm flak gun is not available for prestige until you reach level 9. I would recommend grabbing the Auxiliary U-Boat from the shop (they're free) and use that. Don't bother reloading the torpedoes or fuel, just discharge it when you're out of ammo and get a new one.

Ok. Thank you for your response. I did finally get the flak gun and building is progressing.