Hull damage may be difficult or impossible to repair and will cost you. As you said, 180000 tons didn't get you a promotion or a new boat. Had you returned with no damage and perhaps finished three or so objectives, you may have been rewarded a promotion and/or a new boat. Tonnage is good, but finishing more objectives is better. The top brass likes it when you follow and complete orders successfully and bring your boat and crew home undamaged.

As for carry over, not sure but I would guess yes, the retro damage done earlier may require you make up the difference. i.e.,,,you started the second patrol in the hole with a negative number so to speak. I tend to beleive it's basically a scoring type system that triggers upgrades and promotions.

Ugh... I finished my first patrol: fulfilled 9 objectives and sunk 150000 tonnage. Reward: NOTHING!!

So how much is enough????? I'm gonna wreck the whole allied fleet until those bastards give me a new ship! :down:

Are you fulfilling your mission objectives? I make it a habit of filling at least four per patrol, when I can; sometimes even to the point of passing up small ships to kill in favor of making it to my patrol area and following orders. I played that way in both stock, RFB and TMO and I generally get offered new commands after the third patrol in each boat.

Yes, I'm fulfillinf my objectives. Like I said: I fulfilled 9 objectives and sunk 150000 tonnage in my first patrol. I don't know what's smarter by the way: keep on fulfilling objectives in my first patrol until they give me a new sub in the second patrol, or: just do 4 objectives in every patrol until I get a new sub. I wonder which works faster... Because I'm doing so many objectives, by the time I end the first patrol I could already have ended my second or third patrol (taking the date into consideration). I'm always crazy about these things...wanna take the best approach to make as much progress possible in the smallest amount of time :).

Oh, another question I had in mind: When you get a new sub, will you keep your old crewmembers? Would be kind of a waste of buying/promoting them if you lose them anyway...

Yes, your current crew comes with you although realistically you should be losing your more experienced officers to command and fill out the crews of other newly constructed boats. The game doesn't simulate this though.

That could be part of the problem from threads I have read. Nobody seems to know 'exactly' why you get a new sub. But one thing that was brought up in another thread is the date being involved. In other words if you are doing well and completing your missions and happen to be in base at the right time, when a new sub is available, then it may be offered to you. But if you are doing 9 missions without returning to base, you may have missed the opportunity to get a new sub due to you being at sea during the time period it was available. This is only a guess from other things I have read, so don't take it as fact.
And if you are at sea for 9 missions, that will take a toll on your crew and may have a negative impact on your rating.

Peabody

I generally slog it out on patrol for 2 months, max. This was generally all that a crew realistically could handle before efficiency drops. This isn't simulated in the game, so far as I can tell. I am pretty happy if I complete 4 objectives, sink between 20-33k tonnage, and then I head home with max. 2 refuelling stops (once out, once homeward).

I get offered a new sub every 3 patrols, without fail.