Due to my profession as a hydrographic surveyor I started collecting navigational and land surveying instruments. Over the years I used, repaired and calibrated a wide range of instruments as sextants, levels, theodolites, transits etc. Due to this I became interested in collecting these instruments as well.

In this section the navigational instruments in my collection are shown, while the geodetic instruments are shown in the Geodesy section of this web site.

The menu at the left is divided in Celestial Navigation, Coastal Navigation, and Distance measurement.

Initially I started collecting from the current era backwards, but soon found out that the early instruments were hard to find and seldom affordable. Wanting to know more about their origin, construction and capabilities I started researching these instruments in 2001.

The research I have done on early modern navigational instruments has only been possible thanks to the help of others.

My first contact was with Peter Ifland who kindly introduced me to Willem Mörzer Bruyns (at that time curator of navigation at the Het Scheepvaartmuseum in Amsterdam). To them I am much indebted as without their help and information my research had never started.

In the meanwhile others were kind and patient enough to answer my numerous requests and questions. Among them are Robert D. Hicks (for introducing me to the work by Thomas Hood), Diederick Wildeman and Anton Oortwijn (both Het Scheepvaartmuseum, Amsterdam) and Sjoerd de Meer (Maritiem Museum, Rotterdam) who supplied me with lots of information on contemporary instruments by allowing me to study period literature in their collections.

Similar I am very grateful to Richard Dunn National Maritime Museum in Greenwich) as without his details of the Valentia astrolabe in their collection the reproduction of that instrument would not have been possible. Of course I want to thank Günther Oestmann of Ars Mechanica for casting the astrolabe.

Especially appreciated is the assistance by Tommy Watt, curator of the Shetland Museum and Archives, who has been so kind to take pictures and measurements of the hoekboog scale in their collection and to let me study that same part and the Kennemerland archives at a later visit. Also appreciated is the cooperation of The Netherlands Institute for Maritime Archaeology (NISA) for allowing me to search their depot which resulted in a fragment of this instrument.

I'm very grateful to Lars Einarsson and Max Jahrehorn (both Kalmar Läns Museum) as without their help and information a detailed reproduction of the 1661 Kronan cross-staff would never have been possible.

I also wish to thank the Zeeland archive (Toon Franken), the National Archive, the National Library of the Netherlands and the Library of the University of Leiden for helping me out on my historic research.

Of course the British book and manuscript collections of the National Maritime Museum, the British Library and Petworth House archives have been indispensable.

Over the years I have written several articles on the topic, finally resulting in my PhD thesis in May 2018. The navigational collection now mainly focusses on reproductions and reconstructions of instruments for celestial navigation from the early modern times (or to be more specific the period 1590 - 1731). In addition to that the original instruments date from the 19^th and 20^th century.