If you are bold and brave, and got the weather on your side (preferably bad weather) you should try to sneak into the western part of the channel and lurk there in mid to late january and early february 1940, you will have a great change at spotting the HMS Royal Oak (Revenge-class battleship, 31000 tons) in the middle of a big convoy there with a very weak destroyer screen mostly consisting of armed trawlers and ASW trawlers. Some large tankers and such will also be present. If you dare to get even closer to the western channel approach you might also spot the Ark Royal (Big fat carrier of some kind, never seen it myself though) protected by some nasty and skilled destroyers. A brave kaleun could easily get 50k+ tons in a single attack run there. I myself bagged the Royal Oak with one single (!) torpedo right at the tip of the ship and managed to get away without even one depth charge launched against me. No saves or reloading of game.
Do not engage anything unless extremely necessary if you are swimming the channel and if you really need to surface to charge batteries and get fresh air head towards the french coast as the french navy seems to be completely careless and neglecting in their naval patrols, the occasional trawler and lone Destroyer can be spotted.
NEVER EVER EVER enter the channel during daytime and calm seas, enemy ships and planes (ansons early on) will make your trip into a pain and nightmare as they will be very mad and irritated about your precense in their front yard. If you manage to get past the straits of Dover you can sail close to the French coast as the proud French navy always seems to be on strike or vacation.
So, from my own experiences:
Enter the channel if:
The date is BEFORE may '40.
The weather is bad and it's night.
You are extremely skilled, brave or reckless...
You are hunting a very specific target or raiding harbours (as stated above by another kaleun)
You are extremely low on fuel and need the shortest route avalible back to Germany.
Do NOT enter the channel if:
Date is past may 1940.
You are sailing in anything bigger than a type-IID or VII-B/C (i.e an IX)
Weather is fine and the sea is calm.
You have not lost your mind.
You do not have serious business there.
However, i do recommend every kaleun to take a trip there at least once to experience true tension, challenge and planning, preferably before the fall of France so you will have enemies on both sides of the channel. Even if it's a-historical, one can always role-play a kaleun and crew in the hunt fore something special and that they will never tell anyone from the Bdu about the trip, or a reconnaissance trip from Dönitz or Raeder themselves, an order above whatever the Bdu says
