ok so ... lost my first boat with all hands. long story short, my chief engineer contracted tuberculosis about 2 days into the patrol. the idea is to treat him using an officer with medical skill set and a first aid kit and let him recover in a bunk and hope like hell it doesnt spread.
well... it didnt, but i found a bug. The items that were in my chief engineers que when he contracted the illness - stuck - in his control so any time i needed someone else to manipulate the bilge pump or ballast valve (in this case) i got the message "this is already in use by another crew member" or something similar to that.
well, we were submerged at the time to do a hydrophone check. went to surface... well... nobody could use the ballast tank!
eventually it unstuck and we got to the surface, right under what i assume was a sunderland. we were strafed with machine gun fire and one of the watch crew was injured.
he took to one of the bunks in the forward compartment, one crewman stood beside him and seemed quite exasperated... another sat on the bunk and tried to calm the wounded man.
next we took a near direct bomb hit to the forward compartment (bad luck that guy) sprung a few leaks, damage to the bulkhead, several light bulbs busted out, electrical system completely shorted, everything forward of the control room plunged into darkness and taking water.
equipped one of my officers with breathing apparatus and spare parts, and sent him to work. ordered the compartment evacuated.
and one of the crewmen grabbed the wounded sailor, and dragged him out of the evacuated compartment and took him to an open bunk where he died of his wounds.
meanwhile, two of my mechanically inclined crewmen are working frantically to get the leaks stopped.
the boat was sinking at this point. it was a race against the clock.
next order of business was get the lights back on. again, they grabbed spare parts and eventually got the lights on. things were starting to look better!
ok, leaks stopped, lights on, now i have to get as many people as possible bailing water to the bilge to get it out of the boat. getting very deep now, depth gauge almost pegged
creaking - groaning
BAM
previous repair to a hatch gave out... there was no saving it now. lost due to implosion.
now for the tips
1. Make sure you have an officer with maintenance skill set, its going to come in handy
2. As early as possible get the sixth officer upgrade, one extra officer comes in super handy
3. Make sure you have someone with medical skill... going to go figure out how to make that happen, but it appears without medical skills -
you cant treat sick or wounded sailors 
4. Check your torpedo load out before you head to sea, you probably wont start with a full load of fish
6. get plenty of food
7. always have an officer at the navigator station, and when he is low on energy, swap him out... you
willget lost at sea if nobody is manning that station and you can get found by assigning someone to it. but it takes several minutes to get found
thats all for now