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View Full Version : Vanishing convoy?


BROJD
09-04-07, 03:59 PM
I had my first ever big-time attack on a convoy on the Rockall Banks in OCT '39. I took out two large tankers on my first attack with five fish and escaped with only some minor DCing.

I circled around the convoy and by 0500 was ready for a second attack, with full tubes. The convoy only had two escorts, one out front and one in back. The wind was blowing at 10 m/s, no moon, no precip, light fog. I maneuvered into what I hoped would be a good submerged firing position. When I popped my scope up I saw two large merchants in the second column from me (the remaining tankers were on the far side of the convoy) with some tramp steamers between me and the merchants. I got a good picture of the convoy on my nav screen when my periscope was up. I was 1700 yards from the nearest large merchant.

I eased forward at PD and had two salvoes ready for the large merchants. I was probably within 100-200 yards of the first column when I popped my periscope up, but there was nothing there. I left my scope up and couldn't get any contacts either through my scope or on my nav screen (with the crew), and everything from the hydrophones was gone except for the front escort.

Eventually, the two tramp steamers in the nearest column came up on my hydrophones and on my periscope. Then I got a view of the rear escort 3000 meters away. But nothing else on my hydrophones or visually.

I continued to ease forward and used some left rudder to try to follow where the convoy had been. After about 5-10 minutes everything suddenly came back up on my hydrophones and visually. I ended up taking stern shots at the merchants from 2800 yards. Wasted fish.

I'm not sure what happened:

1) Was I so close to the nearest ships that they blocked out the sound (and sight) of the rest of the convoy? It was very dark, but that doesn't jive because it lasted so long and I didn't regain any contact until the convoy was well past me.

2) Does SHIII model fog banks? That would explain the lost visuals but not the loss of the hydrophone contacts. And I did get a visual on the rear escort 3000 meters away.

3) Just a bug in the game? Has anything like this happened to anyone else?

I still ended up with my most successful patrol, but I was flummoxed when the big fat juicy convoy escaped the second time.

CapnMike U-69
09-04-07, 11:51 PM
Hi, I've had that before also, and sometimes a very quick change of the hydrophone officer fixes it.
Also the Hydrophone (early ones anyway) dont s
'see' the full 360 degrees around your Uboat, and don't pick up contacts behind you - or not nerarly so weel anyway. Normally a change of heading towrds the contacts position also fixes the problem. Fog banks won't stop the Hydr working... , but a sudden increase in speed (above speed '2), can also eliminate the contacts in some instances... I have found much reduced Hydr range when using speed '3', for example unless contact is almost directly in front of you.
Hope that's useful ?
Capn. Mike

BROJD
09-09-07, 12:23 PM
Thanks for the thoughts. Next time I'll try to change out my sonar operator, which might have been part of the problem (second patrol, so all of my guys are quite green).

But I still don't know why I couldn't see any of the ships through my periscope (or my crew couldn't plot them on the nav screen).