GWX difficulty is based on history. from 1939 to 1942-43 the German Submarine Force ruled the seas. Sailors often said there were more U-boats in the water than there were sharks.
The greatest difficutly came when the "arms race" started between the allies and Germany.
around 1942 The allies developed a perfected radar that could pinpoint a surfaced u-boat.
several boats were lost.
the Germans responded by developing a radar detector that would give sub crews advanced notice of approaching radar signals.
after 1943 the allies responded by developing radar capable of operating on a different wave length than the detectors rendering the German detection systems virtually useless. this type of radar could even detect a raised periscope or snorkel sticking out of the water in relatively calm seas.
the germans came up with different detection systems throughout the remainder of the war but the allies were always a step ahead, and the german detection systems were always more or less of no use to the crew.
the allies by 1943 were so deep into the secrets of the enigma that virtually
every radio signal sent from a German U-boat would pinpoint its location on the sea to within a radius of something like only a few miles.
once the allies plotted the radio positions, planes would search the area and would often find and kill the boat. If the planes found nothing, another plot would be made when the next signal was intercepted. then you could establish a basic course for the U-boat. Hunter killer carrier groups zeroed in on the boat.
by 1944 - 1945 sinking a U-boat was like shooting fish in a barrell... though the u-boats were still a potent threat to allied shipping, the aircraft, radar, planes, destroyers and carriers had come under expert guidance and had perfected their tactics of hunting u-boats.
look at historical loss rates for each year of the war.. and you decide when it got historically "hard" in real life... (notice the spike in 1943)
Year - Uboats lost - average per month
1939 - 9 lost - 2.25 per month average (*4 months)
1940 - 24 lost - 2 per month average
1941 - 35 lost - 2.9 per month average
1942 - 86 lost - 7 per month average
1943 - 242 lost - 20 per month average
1944 - 250 lost - 20.8 per month average
1945 - 120 lost - 24 per month average *
* keep in mind the war only lasted 5 months in 1945, given the 1945 average its possible to assume that over 300 u-boats could have been sunk in 1945 had the war laster through the remainder of that year.
in GWX... in 1943 onwards, you will encounter aircraft every day, sometimes many times per day if you sail surfaced much. often times after encountering aircraft a few times they will have provided your location to either a Hunter Killer group or some random destroyers who will find you.
i would estimate your chances of escaping a hunter killer group after 1943 are around 1 in 50.
