It tells me that the submarine is "Undefined" and cannot be used for the campaign. What can I do about it?

Glad to hear it! I'm still trying to work out various kinks regarding mission starts in the campaign, but I believe I am getting close.

If there are any issues that need worked out, or if you want to splice it into a new ship design and need help, let me know.

I have the feeling that the ai and wayponts are on every single computer different. i have no problems with the ai at all on this sub.
This sub is great and is the best submarine so far ive played in barotrauma. sometimes it happen when i turn one gun on/off it gives a shot away. and sometimes the guns fire all the time after starting the round but thats quick fixed by just put ammo out before docking and next round turn autocannons on and off then it works. LOVE THIS BOAT MAN!

Good work with the automated guns, but the waypoints for the AI seems to be messed up (AI cant open doors etc.)
I tried many submarines, just too see that the AI pathing is not good.
Hope they will fix that soon, want to play solo!

a large array of motion detectors and a bit of math. If you want, you can give it a good look in the sub editor. let me know if you can improve it.

how did you make the guns fire automaticly? thats a realy cool thing