Patrol Info

Hello, I have just come back to playing silent hunter 3 with GWX 3.0 Gold installed and am on patrol 6 and have not come across a single ship, I am staying on the surface all the time and sailing around the UK coast line, I have been attacked by aircraft and that's it. Is this normal. On patrol 4 I even sailed straight into Plymouth harbour and there was no ships at all. All rather strange. Any ideas anyone.