Patrol Question
 

Sooooo many questions.....

Ok, you're out on patrol, you've just been assigned another territory to hunt in however if you go there you're going to need a tow back to base due to lack o petrol.

Do you get dinged for returning with an uncompleted objective?

Not really, the game only looks at how much renown you've earned during that patrol.

Not really, never EXCEED 1/3 speed for chasing the bad guy or normal patrol speed. You will get back with a few gallons to spare. :D

Actually it's about 9.5 knots that gives the best mileage in Fleet boats. What comes to the OP's problem the game gives you new objectives until your fuel is ridiculously low, something like 10%. If your new objective with 15% of fuel remaining(you really should be at or close to base at this point) is somewhere around the Yellow Sea with 20-25% required to get back to Midway, you really have no choice but to go back and suffer the consequences. If you had done well before this happens, sinking a decent amount of tonnage and completing a couple of objectives without damaging your sub seriously, your career will most likely continue like nothing ever happened. Personally I never request new objectives if I don't have plenty of fuel to spare.