What is "opduwer"

An opduwer or opdrukker is a small tug- or towboat that was used in the Low Countries to push barges on inland waterways. Opduwers were predominantly in use in the first half of the twentieth century. During that time the internal combustion engine got adapted for inland shipping. Earlier, barges were propelled either by sail or by towing from shore by horse or manpower. Fitting an engine and propeller to an existing barge was found cumbersome however. It was easier to construct a small tugboat and use this to propel the existing barge. Opduwers were built between about 1910 to 1940. A large number survive as pleasure craft.