Specht, C.; Specht, M.; Cywiński, P.; Skóra, M.; Marchel, Ł., and Szychowski, P., 2019. A new method for determining the territorial sea baseline using an unmanned, hydrographic surface vessel. Journal of Coastal Research, 35(4), 925–936. Coconut Creek (Florida), ISSN 0749-0208.

This article discusses a method of determining a territorial sea baseline, which establishes the boundary of maritime zones (inland waters, territorial sea, contiguous zone, and exclusive economic zone) of a coastal state. So far, only approximately 200 of the 430 sea borders have been delimited, which is less than half of all boundaries. The reason behind that omission (apart from the legal, technical, and measurement-related aspects) is the issue of baseline measurement methodology. The aim of this study was to develop a method for determining a territorial sea baseline using an unmanned hydrographic vessel in a 400-m-long water body with a sandy bottom. The measurements were performed with a small, unmanned surface vessel with a global navigation satellite system (GNSS) receiver (Trimble R10) installed with a miniature singlebeam echo sounder (SonarMite BTX). These devices enabled measurements by the hydrographic method in the coastal zone at a depth below 1 m. The measurements involved determining the internal border of the territorial sea and creating a bathymetric chart with isobaths using geodetic software. To verify the results of tests conducted with an unmanned vessel, an additional (reference) measurement was taken in the same water body by the geodetic method with a GNSS receiver and a position accuracy of 2–3 cm (p=0.95), which involved developing a digital terrain model by the “stop and go” method. The geodetic measurements were conducted on the same sounding lines as those of an unmanned hydrographic vessel—by the direct measurements performed with a geodesist in water at a depth of 0 to 1 m.