International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 6
Number 3
September 2012
Marine transport development causes the increase of
the intensity of ships traffic and ships dimensions.
The navigational risk increase requires more sophis-
ticated methods of its assessment. Marine accidents
such as grounding are very rare and serious safety
analysis should also include incident (near misses)
analysis. The incident analysis is very important fac-
tor in navigational safety analysis due to the inci-
dents are usually not reported. Probability of the
ships grounding is one of the most important factors
influencing the navigational safety [2]. Based on the
data from HELCOM in 2008, there were 60 reported
groundings in whole Baltic Sea, and 32 of them
were reported in the south western Baltic Sea. As it
is shown on Figures 1 and 2, in 2009 the number of
reported groundings decreases to 38, but still about
half of them were reported in south-western Baltic
Figure 1 Grounding accidents between (2000-2009) in south-
western Baltic Sea
Figure 2 Grounding accidents between (2000-2009) in Baltic
Incidents Analysis on the Basis of Traffic
Monitoring Data in Pomeranian Bay
L. Gucma & K. Marcjan
Maritime University of Szczecin, Poland
ABSTRACT: In this paper preliminary analysis of grounding incidents was presented for the future use in
navigational safety management system development. The analysis is focused on the area of Pomeranian Bay.
Grounding incidents model is created with use of AIS data. The distance of vessel from the dangerous depth
and draught/depth ratio was considered as the main factors of navigational incident in presented model.
Figure 3 Ships groundings on southern Baltic, analysed area [4]
Presented in this paper analysis of grounding in-
cidents is devoted to the Pomeranian Bay area exact-
ly the area between 13
00’E - 15
00’E and 54
00’N - 55
N. This area extends between Born-
holm, Rügen and the approach to Świnoujście. It
may be considered as costal area, where some places
have relatively low depth. Those are depicted in
Figure 4. Regions with depth of 10 m or less extends
around the Rügen Island, around Bornholm close to
Polish and German shore and also north of approach
to Świnoujście.
Figure 4 Map of selected area with isobaths.[5]
Model used for determining the grounding incidents
on selected area. The model is based on AIS data,
from where static and dynamic data allow one to de-
termine the information on the ship and its positions.
Application written in C# [3] consists of three sec-
1 First section decodes data retrieved from the AIS
and records the routes of vessels navigating with-
in the analysed area. Data is segregated and writ-
ten to the appropriate database tables. Vessels of
6m depth or more are taken into account.
Figure 5 Database table with AIS dynamic data.
2 Second section examines individual positions of
the vessel in terms of distance from depths. The
depths of less than 140% of vessel’s draught are
taken into account. Then the lowest depth, and
the smallest distance to this depths is recorded.
Figure 6 A diagram of lowest depth and distance selection.
3 Third section is a model of positions extrapola-
tion. On the basis of dynamic data this part of
programme is searching for the previous position
(φ(t0), λ(t0)) and following position (φ(tn), λ(tn))
of the vessel in vicinity of the dangerous depth.
Both positions are taken into account only if the
time difference between them and the reference
position (tr), λ(tr)) is less than 6 minutes. Ex-
trapolation algorithm calculates every second po-
sition and the distance from the depth between
the previous, reference and the following posi-
tion. The result is a position of a vessel that is the
closest to the smallest depth in vicinity of the ves-