I am stuck here too. I can promote to general, this will bring the elder sub down to 13. And I can promote to security chief, but this brings it only down to 12 because the shield isn't charging fast enough. Smuggler and helmsman are obviously not needed. I don't need to get faster away from Kyburz. Pirate is also not needed at Kyburz because I can send a sub to one of the other outposts and I get sub to sub combat. Double agent, assassin and saboteur are all good to get rid of the other sub. Inspector could help to survive the elder sub, but I can't get it to Kyburz in time. And I don't see how the pirate at vintgar can help. I can only target the infiltrator sub, but this doesn't help with the elder too. I'm totally lost.
Edit: Ok, thanks to Stefan i got it now. It's so simple once you found the solution.