Good question! I could find nothing in all my Princess literature or on their website about pool hours. But I don't recall ever seeing any hours posted. A pool will occasioally be closed for cleaning or maintenance; but it seems there has always been at least one pool open. And I have seen the hot tubs being used well into the wee hours (okay, bad choice of words).
Hi Martini Mike, welcome to Cruise-Chat. I've looked through my Patters as well and can't find any hours posted. Which ship are you sailing on? It seems to me that there was a pool open somewhere on board most of the time. I think they even had the pool open by the MUTS while the movie was playing. Best wishes for a great cruise, and once again, welcome aboard!