Bah, CTD after a long patrol :(
 

My first one too. I saved the game midway so its not all lost.

I came across a large merchant convoy escorted by 3 destroyers in the Jawa straights while on my way to patrol in the south china sea. I managed to sink over a 100 thousand tones of shipping. I think thats about 4 large merchants and all 3 of the destroyers. I got hounded by aircraft and used every single round of ammunition including the deck guns. During my surface engagements a destroyer managed to flood my aft torpedo compartment leaving me slightly crippled but still running, and I hadn't got to the patrol area yet. I decided that enough was enough and we had done enough damage and headed back to fremantle (whilst being hounded by Jap aircraft). I got to port and refit but I should have saved because then I CTD (for the first time) and lost my progress :(

All that for nothing. I was so proud of myself managing to get all that shipping and get back to port.

I had a good patrol where I found a convoy and I sunk all 12 of the ships in it, while damaged and out of ammo and heading for home I didn't save it (DOH) and got a CTD about half way to Midway.

From now on everytime I reach a reasonable contact, or spend a long time at sea I save it just in case.