There is a mod called SH3Contacts by Nicholas
http://www.subsim.com/radioroom/down...o=file&id=1402 which will increase contacts to your liking.
It is especially useful in the areas South of England and in the Irish sea, where there is a lot of traffic. There is also air cover, a plethora of destroyers and shallow waters, making it dangerous to be there. It is necessary to tract vessels by sonar since you can't run on the surface. When you finally ID the vessel it is often a tug or a fishing boat (as it would be in real life). A contact of a war ship might be a deadly destroyer or an armed motor launch.