The job was to sink freighters.
But in favourable position they could/should attack destroyers and escorts. They shouldn't get after them, risk anything to attack them, but an escort at 12 kts merrily crossing the bow in calm waters?
Ready tube 3 - Eto - Impact pistol only - 2.5 meters depthsetting - distance 1200 meters - bow left - AOB 70 - revolutions for 12 Kts, Herr Kaleun - LOS!
The homing torpedos were designed to sink escorts - for targets doing 12 Kts or faster. A wolfpack sinking half the escort screen would have had a feast on the convoy.
There were some problems still to solve: the sensors were unreliable, could be easily distracted (by foxers - towed devices making noise), most of the time the weather conditions were not good enough to attack destroyers or escorts. They didn't even attack freighters in bad/unsuitable conditions.
(should be SH3 sea/wind state ~ 10/11 and above)
DDs/DEs/Other sunk by German Uboats:
USS Bristol (DD-453) - U371
USS Buck (DD-420) - U616
USS Jacob Jones (DD-130) - U578
USS Leary (DD-158) - U275
USS Reuben James (DD-245) - U552
USS Fechteler (DE-157) - U967
USS Fiske (DE-143) - U804
USS Frederick C. Davis (DE-136) - U546
USS Leopold (DE-319) - U255
USS PC-558 (Submarine Chaser) - U230
USCGC Alexander Hamilton (WPG-34) (Coast Guard) - U132
USCGC Acacia (WAGL-200) (Coast Guard - former Minelayer) - U161 (sunk by Gunfire!)
USS Eagle Boat 56 (PE-56) (Gunboat) - U853
USS Plymouth (PG-57) - U566 ((Gunboat)
USS YP-389 (Patrol Boat) - U??? (sunk by Gunfire!)
That's just the US Americans.
Here have the British:
https://en.wikipedia.org/wiki/List_o...n_World_War_II
__________________________________________________ _______________
EDIT: (06/30/16) Flower Class Corvettes attacked
successfully by German Uboats:
Canadian
HMCS Alberni (K103) - U 480 (escort) (= while assigned to a convoy as escort)
HMCS Charlottetown (1941) - U 517
HMCS Lévis (K115) - U 74 (escort)
HMCS Regina (K234) - U 667 (escort)
HMCS Shawinigan (K136) U 1228
HMCS Spikenard (K198) - U 136 (escort)
HMCS Trentonian (K368) U 1004 (escort)
British Royal Navy
HMS Abelia (K184) - U??? (escort) T5/damaged/sold
HMS Arbutus (K86) - U 136 (escort)
HMS Asphodel (K 56) U 575 (escort)
HMS Bluebell (K80) - U 711 (escort)
HMS Fleur de Lys (K122) - U 206
HMS Gladiolus (K34) - U 553 (escort)
HMS Picotee (K63) - U 568 (escort)
HMS Pink (K 137) - U 988 (escort) damaged/loss
HMS Polyanthus (K47) - U 305 (escort)
HMS Salvia (K97) - U 568 4 Torps Fan
HMS Vervain (K190) - U 1276 (escort)
HMS Zinnia (K98) - U 564 (escort)
French Flower Class
FFL Alysse (K 100) - U 654 (escort)
FFL Mimosa (K11) - U 124 (escort)
Norwegian Flower Class
HNoMS Montbretia (K208) - U 262
These are only successful attacks! They probably tried more often!
__________________________________________________ _______
Edit2: (07/01/16)
Castle Class Corvettes
HMS Hurst Castle (K416) - U 482 (escort)
HMS Denbigh Castle (K696) - U 992 (escort)
------------------------------------------------------------------------------------------
Frigates attacked by German Uboats, but not sunk (damaged beyond repair/all declared loss)
Canadian River Class Frigate
HMCS Chebogue (K317) - U 1227 (escort) (= attacked while assigned to a convoy as escort)
HMCS Magog (K673) - U 1223 (escort)
British River Class Frigate
HMS Cuckmere (K 299) - U 223
HMS Lagan (K 259) - U 270 (escort)
HMS Teme (K458) - U 246/U 315 (escort)
British Captain Class Frigate (ex US Evarts & Buckley)
HMS Goodson (K480) - U 984 (prob. escort)
HMS Bickerton (K466) - U 354 (escort)
HMS Whitaker (K580) - U 483 (escort)
HMS Mounsey (K569) - U 295 (escort)
HMS Affleck (K462) - U 486 (sank HMS Capel (K470) the same day)
HMS Manners (K568) - U 1051 (Hunter Killer)
HMS Redmill (K554) - U 1105 (patrol)
HMS Goodall (K479) - U 286 (escort)
Most have been attacked with G7es.
_________________________________________________
Edit4: (07/03/16)
Frigates directly sunk by German Uboats
Canadian River Class
HMCS Valleyfield (K329) - U 548 (transfer)
British River Class
HMS Itchen (K 227) - U 666 (escort)(Gefallener Engel - Aktungbby)
HMS Tweed (K 250) - U 305 (escort; patrol)
HMS Mourne (K 261) - U 767 (patrol)
Captain Class (ex US Evarts & Buckley)
HMS Blackwood (K313) - U 764 (escort; patrol)
HMS Capel (K470) - U 486 (patrol)
HMS Gould (K476) - U 358 (Hunter Killer)
HMS Bullen (K469) - U 775 (escort;patrol?)
__________________________________________________ ______
Edit3: (07/01/16)
Sloops sunk/attacked by German Uboats
British
HMS Penzance (L28) - U 37 (escort)
HMS Culver (Y 87) - U 105 (escort)
HMS Dundee (L84) - U 48 (escort)
HMS Puffin (L52) - Rammed a German Midget Submarine Seehund (midget torpedoes exploded/damaged/loss)
HMS Stork (L81) - U77 (escort) (Walker's Bittern Class Sloop - damaged/repaired)
HMS Woodpecker (U08) - U 256 (escort)
HMS Chanticleer (U 05) - U 515 (prob. escort) (damaged/loss)
HMS Kite (U87) - U 344 (escort)
HMS Lark (U 11) - U 968 (escort)
HMS Lapwing (U 62) - U 968 again (escort) (other patrol)
Australian
HMAS Parramatta (U44) - U 559 (escort)
__________________________________________________ ______