I don't know about your superstitions.
G7a torpedoes aren't really ideal for U-boats because their wake can easily be spotted unless you attack at night or rough seas. The electric TIII models don't leave bubbles thus the target can't sight them.
If you've never been to the Mid-Atlantic, you have missed the essence of the tonnage war against Britain since her lifelines were the convoys sailing from America through the North Atlantic, exactly where U-boats supposed to hunt. Operating in shallow waters near the coast is dangerous especially later in the war and harbour raiding isn't too realistic either.
I suggest you take a trip to the Atlantic along the convoy routes and you'll see the difference.
