The vikings were illiterate, they didnt put anything in writing, so it would be very difficult for them to rely on the sun for navigation, and i tend to think, why would they, because for thousands of years, people in the northern hemisphere, have used polaris for navigation, its allways in the northern sky, and the higher it is, means the further north you are, the lower it is, means the further south you are, only thing you cant work out from observations of polaris, is how far east or west you are, and you cant do that with a sun stone either, even if it lets you see the direction of the sun, an hour after its gone down, all it tells you is the direction west is, and anyone who goes to see, understands that when the sun goes down, the stars come up, if you see sirius, in early evening, and its on your beam, when you are heading for some island, and you know you are going the right dircetion, it will be on your beam the next evening, I am not saying you are wrong, but to me, seems like an overcomplicated way of doing things.
The other thing is, in the area of the north atlantic where the vikings spent a lot of time. The wind, and the waves, nearly always come from the west, I spent a lot of time at sea in that area, and you know you are heading west when you get into the north atlantic, just by where the waves are coming from, when you are punching into it, you are going west, when its on your stern, you are going east. You may get it coming from north of west, or south of west, but it will never be from due north, or from due south, which is why, if you look at every british city, the poor part of the city is always in the east, and the rich part, is always in the west, reason being, during the industrial revolution, the factories were built within the city, and the smoke from the factories blew from west to east, so the owners and wealthy people, built their houses on the west side of the city, and the poorest people, ended up on the east side of the city, a thing that still lives on today, in the uk, where the east end of a city, is still the poorest part of the city, and the west end, is the most desirable.
Al, with all due respect, your statement that Vikings were illiterate is historically absurd and false. The runic alphabet was used by the early Germanic tribes and the Norse as a form of written communication until the latin alphabet predominated in the 12th Century due to the influence of the church. There is a wealth of history, poetry and the famous sagas that were recorded in Runic inscriptions. Before you make assertations as truth to a readership that may not know early world history, you have a responsibility to be accurate and knowledgeable in your assertions. Don't lump the Vikings with other cultures that were illiterate. The Vikings were a culture that possessed Science, Art, Literature, Technology and a written language. They also possesed a trait that has been lost in the modern world: bravery, honor and cultural pride. You might want to read about this further. Best, Ron
en.wikipedia.org/wiki/Runic_alphabet