2006 Volvo v50 2.4i TOWING (or S40)?

Towing capacity on a V50 is 2000 lbs, so it's probably not a good fit for you. Even if the boat is 2000 lbs, which would be your low estimate, you are pushing the limit. You also still have to figure in all the other stuff you pack in to it including yourself and pengers. An '06 S40 would be the same.