3D Measurement of a Gajeta using TRITOP

The GAJETA is a small traditional fisher boat from Croatia. It is made of wood, approximately 7 to 12 meters long and was used in the Mediterranean Sea along the Adriatic coast for fishing and transportation between the islands. The boat excels by its rounded bow and stern, its high carrying capacity and its good navigability, especially on the rough sea. However, when less expensive plastic boats appeared that were mostly produced by foreign manufacturers, the number of authentic boats drastically reduced.

One of the few still existing Croatian shipyards, specialized in the construction and repair of wooden boats, is located in the small town of Nerezine on the island Losinj. Enthusiastic about the beauty and navigability of its 8 m long GAJETA, the Lekic family decided to restart the production of these wooden boats. They own a boat with excellent characteristics and have the infrastructure, the knowledge and the necessary experience in building wooden boats. Now, with the help of modern technology, they want to revive traditional boat building.

Making wooden boats is a big challenge. Modern technology simplifies and quickens the manufacturing of products having reproducible characteristics. In order to make it possible to create a faithful copy of the Nerezine boat, the Croatian company TOPOMATIKA performed a 3D measuring of the boat’s shape using the photogrammetry system TRITOP of GOM.

Approximately 300 reference point markers (adhesive paper with white points on a black background) were applied to the boat in order to exactly define the shape of the hull (fig. 1). Then, several images from various directions were recorded with the digital camera and loaded into the notebook PC. The TRITOP software automatically identified all reference point markers in the digital images with high accuracy.

Now, measuring the hull using TRITOP is fast, flexible and precise. The created mathematical model of the boat is a faithful copy of the original. Customer wishes can easily and correctly be implemented and optimal planning and execution of production is possible. A CNC milling machine may use the CAD data to directly cut the shape of the ribs into the wood. For small lots, the rib shapes defined in CAD are printed on a plotter, manually transferred to the wood and sawn out.

We would like to thank the Nerezine shipyard for their trust in TOPOMATIKA and for the permission to publish this report.

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