indeed DublinPilot, people should read the question.
Depends on the regime you fly under, but even in the JAA I'd say yes you can. As PIC you can delegate certain aspects of the conduct of the flight to others but still remain responsible for the flight. Otherwise how could a long haul airline captain go have a kip in his bunk when half way across the atlantic? All you are doing is delegating the task of looking out of the window, if the other person is qualified to do and the regulations say he can, then why not?