The original posters map and directions are the same route Gunther Prein took when he sunk the battleship Royal Oak in 39'.
There is a map of his attack here.
WWW.U47.org
"The stern still touches the cable, the boat becomes free, it is pulled round to port, and brought on course again with difficult rapid manoeuvring, but... We are in Scapa Flow!"
0027 hours 14th Oktober 1939
In GWX III you can find the Royal Oak on that date but its out of place about 4-6 miles to the north west of its original position