Sun compass by day, stellar by night. In scouts we learnt that if you take half the distance between the hour and minute hand on the hour, then that point will mark north. EG at 10.00 am the halfway point is 11.00 so you would at least get a rudimentary heading of north. Good enough to keep you going in a general straight line, but you better hope the water hole you are looking for is the size of Lake Eyre. When it is overcast you could always use the Sylvia that you kept in the back pocket for emergenciesas being a scout/venturer/rover you would not venture out unless you were fully prepared.