86 
Figure 5: Areas covered by charts Gulf of Koper and Gulf of Piran 
The land section is charted in yellow and its 
appearance differs from usual topographic maps, 
because for nautical charts the important elements 
of the land section are landmarks, aids to 
navigation and type of coast (figure 6). The land 
section of the Gulf of Koper chart was extracted 
from vector and raster topographical maps at a 
scale 1 : 5000 and from colour aerial photographs. 
All topographical elements were transformed from 
state coordinate system in Gauss-Kruger projection 
on Bessel ellipsoid to Mercator projection on WGS 
84 ellipsoid. For navigation reasons the Mercator 
projection is used. Ellipsoid WGS 84 is applied due 
to the increasing usage of modern navigation 
equipment - GPS, which is used daily on practically 
all vessels. There is also a tendency for unique 
reference ellipsoid all over the world. Furthermore, 
the IHO's exchange standards S-57 for digital 
hydrographic data transfer and S-52 for electronic 
navigational chart (ENC) production establish WGS 
84 as the only legitimate reference ellipsoid. 
The maritime section of the chart was transformed 
from geographic coordinates on WGS 84 ellipsoid 
to Mercator projection and was joined and matched 
with the land section. The reference surface for all 
heights is mean sea level (MSL) while the reference 
surface for depths is mean lower low water 
(MLLW). Areas shallower than 10m are charted in 
blue tint, deeper waters are white. Drying heights 
are charted in green. All lights and buoys have their 
light characteristics alongside the symbols. Special 
attention has been paid to restricted areas: harbour 
entrance channel, construction area in the harbour, 
Strunjan nature reserve, the Debeli Rtic natural 
monument,, marine farms in Strunjan and Lazaret 
and the marina and shipyard at Izola. Also bottom 
type and wrecks are charted.