nautical charts, was given the opportunity to 
educate one of its cartographic experts at the 
International Maritime Academy (IMA) (Karnicnik, 
1998). Hydrographic education continued last year 
as it will in the future. 
HYDROGRAPHIC SURVEY 
A nautical chart is a combination of topographic and 
hydrographic sections. The topographic section is 
acquired by a geodetic and photogrammetric 
survey of the land area of a chart, and is 
represented quite schematically. The hydrographic 
part with all navigational data is the most important 
part and must be complete and made with 
maximum precision. Hydrographic data are 
acquired by hydrographic survey. The survey is 
accomplished by a hydrographic survey vessel in 
accordance to IHO standards. Slovenian sea is too 
small for it to be reasonable to have our own 
equipment for such a demanding survey. From this 
reason Navoceano (Department of the US Navy, 
Naval Oceanographic Office) did the first survey of 
our sea with their survey vessel Littlehales and two 
HSLs (Hydrographic Survey Launch). During the 
survey both IGF and the Ministry participated in the 
survey and provided liaison between the Slovenian 
Government and Navoceano. A connection was 
established via Internet between IGF and the 
vessel. At the same time the team of cartographers 
was organized to check and archive all the 
transferred data (Karnicnik, Radovan, 1998b). 
The first part of the survey was a geodetic survey of 
all reference points and aids to navigation. A 
network of five GPS reference points was 
established on land to provide sufficient support for 
precise positioning (figure 1). Those points were 
used for positioning a tide gauge in Koper harbour 
and all aids to navigation (lighthouses, lights, buoys 
and landmarks) (figure 2). All lighthouses, lights, 
buoys and landmarks were documented and for 
each a photograph was taken. All light 
characteristics were checked and every aid to 
navigation was described. For some lighthouses 
and lights, usually the most important, a VHS 
videotape panorama was taken. 
Figure 1: GPS reference network 
Nowadays practically all navigation is done by GPS 
satellite navigation. This involves the use of modern 
navigational systems with electronic charts directly 
connected to GPS and positions plotted directly on 
the screen. The precision of such positioning is 
increasing every year. That leads the surveyors and 
hydrographers to conduct a survey of all reference 
points and aids to navigation to meet these 
requirements - a high precision survey with direct 
plotting of ship's position. 
Figure 2: GPS positioning of aids to navigation 
The hydrographic survey which followed was 
completed in about one month. In this time the 
Slovenian sea between the border with Italy and the 
town of Portoroz was surveyed with various 
instruments (figure 3). The following parameters 
were surveyed: 
• the depths by multibeam sonar (simultaneous 
acquisition of 32 depths), 
• the depths by singlebeam sonar (close to 
coast),