The story takes place on an Earth-like world. A Viking-like sailor is headed west on an ocean to explore unknown areas of his world. He is standing on the deck of his ship and sees something big and metallic pass overhead. It appears to land somewhere to the north. He doesn’t know what it is but it is a landing craft from an Earth spaceship. And the spacers have selected this area for their camp because it was an uninhabited area of this world. I seem to recall that the sailor and the spacers interact.
That is all I remember and some of it may be wrong because it has been many years since I read it. I don’t think it’s a book but I think it was longer than a short story.