dont quote me on this because im not sure its 100% accurate, but didnt america design the radar capable of detecting german u-boats? imagine if america had never done that. germany could of quarentined britain like america did in the 60's with cuba. with no supplies coming to britain from other countries and its factories being bombed on the homeland, england would of eventually been bled of supplies untill she was forced to ether surrender or be crushed.
No, the Germans were doing a damn good job stopping our convoys up till mid 1943, they just didn't have enough uboats to seal the deal. Also, it wasn't any 'american' radar (all three powers had it and even the Germans even had some basic radar jammers on the u-boats), it was air power, that crushed the uboats. Uboats had to surface, and if you can have constant patrols of aircraft, you can sink uboats all day.
overview numbers..
Allies Germans
30,248 merchant sailors 28,000 sailors
3,500 merchant vessels 783 submarines
175 warships
details....
Date tonnage tonnage uboats sunk
shipped sunk
Sep. '39 3297070 153879 2
39-10Oct. '39 3576135 134807 5
39-11Nov. '39 4408689 51589 1
39-12Dec. '39 4466664 80881 1
40-01Jan. '40 4847044 111263 1
40-02Feb. '40 4348820 169566 6
40-03Mar. '40 4970525 62781 1
40-04Apr. '40 5336917 32467 5
40-05May '40 5362873 55580 1
40-06Jun. '40 284113 105193 0
40-07Jul. '40 195825 70193 2
40-08Aug. '40 267618 53283 3
40-09Sep. '40 295335 56328 1
40-10Oct. '40 352407 8752 1
40-11Nov. '40 146613 66438 2
40-12Dec. '40 212590 14890 0
41-01Jan. '41 2651399 126782 0
41-02Feb. '41 2621795 196783 0
41-03Mar. '41 2864121 243020 5
41-04Apr. '41 2620531 249375 2
41-05May '41 3466204 325492 1
41-06Jun. '41 3594684 310143 4
41-07Jul. '41 3765724 94209 0
41-08Aug. '41 4002450 80310 4
41-09Sep. '41 4267134 202820 2
41-10Oct. '41 4203224 156554 2
41-11Nov. '41 3336789 62196 5
41-12Dec. '41 3735419 124070 10
42-01Jan. '42 327357 57086 3
42-02Feb. '42 476451 133746 2
42-03Mar. '42 537980 55706 6
42-04Apr. '42 431664 82924 3
42-05May. '42 607247 59041 4
42-06Jun. '42 700235 54769 3
42-07Jul. '42 476065 74313 11
42-08Aug. '42 544410 60532 9
42-09Sep. '42 485413 57526 10
42-10Oct. '42 619417 5686 16
42-11Nov. '42 729160 53868 13
42-12Dec. '42 330816 4853 4
43-01Jan. '43 203128 25503 6
43-02Feb. '43 359328 75 19
43-03Mar. '43 627377 65128 15
43-04Apr. '43 327943 3034 15
43-05May. '43 264853 20942 41
43-06Jun. '43 97753 6083 17
43-07Jul. '43 242145 106005 37
43-08Aug. '43 86579 14133 25
43-09Sep. '43 118841 22905 10
43-10Oct. '43 97407 22680 26
43-11Nov. '43 66585 62452 19
43-12Dec. '43 86967 75471 8
44-01Jan. '44 92278 24237 16
44-02Feb. '44 92923 21616 20
44-03Mar. '44 142944 0 25
44-04Apr. '44 62149 19755 21
44-05May. '44 24424 2873 24
44-06Jun. '44 57875 9008 25
44-07Jul. '44 63351 0 24
44-08Aug. '44 98729 0 35
44-09Sep. '44 43368 0 22
44-10Oct. '44 7176 0 13
44-11Nov. '44 29592 7247 8
44-12Dec. '44 58518 35920 15
45-01Jan. '45 56988 7176 14
45-02Feb. '45 65233 7177 21
45-03Mar. '45 65077 0 33
45-04Apr. '45 72439 22822 53
45-05May. '45 11439 7176 3