From freedom to compulsion. On the relation between science and seafaring in the Netherlands during the 19th and early 20th centuries During the 19th and early 20th centuries, navigation technology in the Dutch mercantile marine became increasingly based on scientific knowledge. Up to around 1860, the expanded use of science was mainly the result of free choice. It is shown that the adoption cannot be fully explained by the growing importance of the Asia trade, the influence of naval officers or the purported advantages of "scientific seafaring". It was also due to the fact that between the 1820s and early 1850s substantial numbers of captains and mates in the Dutch mercantile marine were recruited from the science-minded bourgeoisie. As the mercantile marine fell into a crisis after about 1860, the interest among the well-educated classes in careers at sea dwindled accordingly and the eagerness of seafarers to cooperate with scientists tended to lessen as well. The use of science still increased, however, but from now on as a result of compulsion rather than an act of free choice. Scientists and scientifically-trained experts at various key institutions joined forces with directors of steamship companies to pressure the government into introducing compulsory exams for masters and mates (with a good share of mathematics, physics and astronomy) and issuing detailed regulations concerning the application of scientific knowledge at sea.