| Instrument | : | Hoekboog (Double Triangle) |
| Manufacturer | : | N. de Hilster (original unknown). |
| Country of origin | : | The Netherlands (Original also) |
| Manufacturing year | : | 2009 (Original: at least from 1623) |
After finishing the demi-cross reconstruction I continued with yet another navigational instrument that no longer exists: the hoekboog or double triangle. It is not known who invented the hoekboog, but alike the demi-cross it has been mainly depicted by Blaeu in the early years of its existence.
The instrument is of the same size and has similar features as the Davis Quadrant, but has chords instead of arches. The chords are divided in 60 (upper triangle) and 30 degrees (lower triangle), a ratio also found on period Davis Quadrants.
Although the instrument has been described for at least 91 years by a variety of authors, only two fragments of them survived. Based on these fragments and the descriptions and images found in those period works I made this reconstruction.
After four years of research, I finally was confident enough to create two different versions of the instrument, which took me about 70 hours each. Now the instruments should be a 95% accurate reconstruction of the original, showing two stages in its development.
Materials used on this reproduction are ebony for the frame and scales and pear wood for the vanes. In addition to that the horizon vane is painted white on one side.
I'm very grateful to Diederick Wildeman and Anton Oortwijn (both Scheepvaartmuseum Amsterdam) and Sjoerd de Meer (Maritiem Museum Rotterdam), as they supplied me with lots of information on this instrument and other contemporary instruments by allowing me to study period literature. 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 his collection in 2005 and to let me study that same part and the Kennemerland archives at a later visit in 2006. 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.
An article on the instrument is expected to be published somewhere in 2011, probably in the Bulletin of the Scientific Instrument Society.
If you like to know more, don't hesitate to contact me.