Schull Dutch Skippers on the Lower Rhine from the 15th to the 18th Century

The author's Dutch ancestors were skippers/shipowners on the Lower Rhine river, presumably coming from the port city of Tiel on the river Waal. However, the bits of written information available about them did not provide much more than names and life records back to the year 1691. And earlier times were totally uncharted.
Details about how these ancestors had mastered their life as skippers were unknown. The author wanted more than just to collect names and vital records, but to discover as many generations of skippers as possible and fill their history with lives. But how should he expand his knowledge about people who had no fixed address because they had been traveling on the Rhine between Dutch port cities and Cologne for many years? Fortunately, they already had a family name the author could look for! This was by no means a matter of course, as the research periods date back to the 15th century. This family name and the Internet were the keys to the successful search for clues.