U-11 checking in from the vicinity of Firth of Forth. Our mission had us going up to patrol the freaking Shetlands. After patrolling for over 24 hours and finding absolutely nothing, we caught wind of a convoy heading WSW about 200 kilometers away. We did some calculations and decided we could catch it, and took off at flank speed. We made it to the intercept point, but there was no convoy. After searching for the convoy for several hours, I decided to head back up to the Shetlands. We almost made it back to the patrol zone when we got another update on the convoy. It's now heading SW, directly towards Firth of Forth. So we turn around again and head with flank speed towards the Firth, trying desperately to cut them off. We didn't make it in time.
Finding ourselves right off the river entrance in about the worst weather imaginable (raining, foggy, 14m/s winds, and nighttime) , we submerged and quickly picked up a merchant closing with us. So, running completely off of hydrophones, I set up a shooting position about 450 meters from where the merchant would make its closest pass. Making a hydrophone-based preliminary solution, I was able to fine-tune the solution when the merchant appeared out of the fog. A small merchant, but better than nothing. Took a shot, and at that range, I could hardly miss. The blast from the torpedo rattled the dishes in the mess as we took off to the East. The merchant sank quickly, and I decided to run on the surface for added speed, counting on the weather to conceal me from the destroyers and trawlers. This almost turned out to be a fatal decision, for as we were making tracks, an Armed Trawler plowed out of the gloom astern of us, heading across our wake.
Somehow they didn't see us, but I took us to periscope depth and made like a hole in the ocean. Fortunately, they didn't hear us either, and after he left we were able to surface and run to a safe distance off the coast. I'll probably not do that again.