I lived for sixteen years in Arabia, sailed up the Red Sea, and I have visited most of the countries in the Middle East. The six weeks that we spent in
Egypt were enjoyable and affordable. We also did a Nile River
cruise on one of the riverboats. I speak passable Arabic, and I am relatively fearless about traveling in Arabic speaking countries.
I think a trip up the Nile would be possible, but I suspect that you would sail through miles of
red tape during the trip. Officialdom would not know what to do with you as you proceeded on your voyage because you would fall between the cracks in their bureaucracy. It could go very well or extremely poorly. When we entered
Egypt on Exit Only, we paid someone to fill out 40 pages of documents just to enter the country on a yacht. It was actually easy, because someone knew what papers needed to be completed, and we gratefully paid them for their services. That was a best case scenario.
Along the Egyptian coast, there are many restrictions on where you can
anchor your yacht, and they send officials out to tell you to move if you are anchored in the wrong place. The problem is that you don't know if they really are officials or not.
99.9% of the Egyptians are wonderful people, but they are also very poor. Whenever you stopped the
boat, you would be quickly swamped by dozens of people wanting to sell things to you.
For you to make this type of trip, I would recommend taking on an Egyptian crew
member for the duration of the voyage up the Nile. His job would be to translate, ward off unwanted boarders and sellers of merchandise, do your paperwork, and watch your boat when you were not on board. There isn't going to be much in the way of
marinas on the Nile, and an Egyptian national would be of assistance when when dealing with petty officials and others who tell you everything that you cannot do.
It would be a fun trip to make if you had the right crew
member, especially if he was connected to someone in the
government.