International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 5
Number 4
December 2011
471
1 INTRODUCTION
The main goal of navigation is to handle the ship in
accordance with aim of their movement when re-
quired parameters of this process should be retained.
The inland shipping requires the proper knowledge of
navigators and adequate of navigation bridge equipment
The process of ships movement in water area should
be safely. Its estimation is executed by means of no-
tions of safety navigation. It may be qualified (Galor
W. 2009) as set of states of technical, organizational,
operating and exploitation conditions and set of rec-
ommendations, rules and procedures, which when
used and during leaderships of ship navigation min-
imize possibility of events, whose consequence may
be loss of life or health, material losses in conse-
quence of damages, or losses of ship, load, port
structures or pollution of environment. Very often,
the sea-river ships move on waterways (natural and
artificial) inside of land for hundreds kilometres.
The manoeuvring of ships on each water area is
connected with the risk of accident, which is un-
wanted event in results of this can appear the losses.
There is mainly caused by unwitting contact of
ship’s hull with other objects being on this water ar-
ea. The safety of ship’s movement can be identified
as admissible risk, which in turn can be determined
as combination of probability of accident and ac-
ceptable losses level (Galor w. 2009).
As a result, a navigational accident may occur as
an unwanted event, ending in negative outcome,
such as:
loss of human life or health,
loss or damage of the ship and cargo,
environment pollution,
damage of port’s structure;
loss of potential profits due to the port blockage
or its parts,
coast of salvage operation,
other losses.
The inland waterways are restricted areas those
where ship motion is limited by area and ships traf-
fic parameters. Restricted areas can be said to have
the following features:
restriction of at least one of the three dimensions
characterizing the distance from the ship to other
objects (depth, width and length of the area),
restricted ship manoeuvring,
the ship has no choice of a waterway,
necessity of complying with safety regulations set
for local conditions and other regulations.
The floating craft (ship) during process of naviga-
tion has to implement the following safety shipping
conditions:
keeping the under keel clearance
keeping the safety distance to navigational ob-
struction
avoid of collision with other floating craft.
The Modes of Radar Presentation of Situation
in Inland Navigation
W. Galor
Maritime University of Szczecin, Poland
ABSTRACT: The use of an Analogical Simulator in shiphandling-manoeuvre tests (SIAMA) in waterways
constitutes a useful tool for providing improvements in port design and manoeuvring rules, which, when en-
hanced with other relevant hydraulic studies of Froudian scale models, is a source of valuable statistical in-
formation. The time-scale of physical models fast-time runs complie with the square root of the linear scale,
in this study-case the model time was 13.04 times faster than prototype. More than 1500 official tests having
been undertaken since 1993 by 13 official pilots of three harbours, for manoeuvring and project optimization
in 7 piers, with 10 berths, and radio-controlled ore carriers of 75,000, 152,000, 276,000 365,000, 400,000 and
615,000 dwt. The laboratory facilities belong to the Escola Politécnica of Sao Paulo University, Brazil. The
port area studied comprised fairways, turning basins and berths. The ships and tugs were unmanned, with tug
performance exerted by air fans.
472
Thus the navigation on such waterways is differ-
ent than on approaching waterways and coastal wa-
ter areas. The realization of navigation on limited
water areas is consisted on:
planning of safety manoeuvre,
ship’s positioning with required accuracy on giv-
en area,
steering of craft to obtain the safety planned of
manoeuvre.
The leading of safely navigation requires first of
all the high accuracy ship’s positioning to avoid the
contact with other ships and fixed objects. It can be
natural objects (coast, water bottom) and artificial
(water port structures-locks, bridges etc.) obstruct-
ers. Such kind of shipping is called as pilot’s naviga-
tion. It necessitate the proper. The main elements of
Integrated Bridge System are navigational systems-
satellite, radar, electronic charts ECS/ECDIS. Navi-
gation Integrated Bridge contains the devices of sips
positioning (radio navigation systems including sat-
ellite) and presentation of situation (electronic charts
system ECDIS, radar/ARPA) (Opracowanie...2009).
A vessel’s position in a restricted area should be
considered as the position of its entire waterline area
in the waterway. If the position of a manoeuvring
ship is not known with required accuracy, there is a
risk of navigational accident.
The distance between the hull and another object
depends on the dimensions of required manoeuvring
area within the waterway. For fairways the manoeu-
vring area is considered to be the width of vessel’s
swept path:
The navigational component of swept path width
depends on:
position determination accuracy,
position determination frequency,
methods of converting a position into the water-
way coordinates.
The manoeuvring component depends on a num-
ber of factors. One of them is the time of the naviga-
tor’s, i.e. pilot’s or captain’s response to observed
movement off the fairway centre line, its analysis
and giving a relevant command. The response time
is affected by the same factors as those affecting the
navigational component (mentioned above). The
swept path reserve allows for hydrodynamic phe-
nomena of bank effect or another object on vessel
hull (mainly suction forces).
In the case of a system of continuous position de-
termination, position determination accuracy is the
basic element affecting the swept path width. That is
why it is important to ensure that position determi-
nation is performed with appropriate (possibly high-
est) accuracy.
2 THE MODES OF RADAR PRESENTATION
OF SITUATION
The radar is one of the basic devices which facilitate
safe navigation in various conditions both reduced
and good visibility. The radar as a technical device
significantly helps conducting a vessel by presenting
a proper image of a situation around the vessel. The
use of radio waves for presenting imaging objects
enables a display of a situation that would be partic-
ularly difficult in poor visibility (fog, precipitation,
night). In this way the radar facilitates steering a
vessel in conditions in which human observation is
much hampered, if not impossible (Fedorowski J. &
Galor W. & Hajduk J. 1998). Nevertheless, radar
observation also has some limitations resulting from
the manner radar operates.
The use of radar for navigation can be said to
have two basic goals:
avoidance of collisions with stationary objects
(natural objects such as the shore or bottom, and
artificial objects such as port or other structures),
avoidance of collisions with other vessels.
In both cases the operation of the radar can be di-
vided into the following stages:
detection of an object that results in a graphic
presentation on the radar screen,
object identification on the radar screen by the
navigator,
measurement of the detected and identified object
(its position, movement parameters etc.).
The basic information for the navigator is pre-
sented on the display screen (Galor W. & Galor A.
2008). Presently, the display commonly used on
board sea-going ships and other sailing craft is the
type P display (called panoramic display). The dis-
play, showing a radio-located chart which illustrates
the area surrounding the vessel, makes it possible to
read out the range and direction (heading or bear-
ing). Target echoes are displayed as spots displayed
on the radar screen. Due to easy transformation of
the polar coordinate system of the display into the
Cartesian coordinate system of marine charts plus
‘bird’s eye view’ imaging, the image interpretation
is generally simple, except for a few particular situa-
tions. In spite of all the advantages of the panoramic
display that make its use quite common, it should be
noted that there are a number of shortcomings that
limit substantially its range of applications. These
are situations where navigation takes place in re-
stricted areas, mainly rivers and channels or canals.
When the range scale of observation is the same for
the entire displayed area around the vessel, it often
happens that the useless part of the screen (land be-
yond the shoreline) makes up 70% or more of the
observed screen. Taking into account the width of a
restricted area, the screen diameter (width) and the
473
minimum operating range scale, it may turn out that
using radar in such a situation is much more diffi-
cult.
The faults of that panoramic display may be
largely eliminated by the method that presents the
situation around the vessel as perspective display al-
so known as type B (U.S. Radar…2006) perspective
called sometimes also cineramic presentation
(Brożyna J. 1984).
3 PANORAMIC PRESENTATION
Modern shipboard radars use mainly type P pano-
ramic displays (PPI-Plan Position Indicator) for im-
aging information on the position of detected targets.
Imaging on such a display resembles a chart and is
‘drawn’ in the polar coordinate system. Figure 1 pre-
sents a real image seen on the radar screen with the
type P display recorded during a voyage of a vessel
on the River Odra (Poland).
Each detected target is presented in position de-
pended on its real distance (D) and bearing (NR).
Formerly the radial scan cathode tube ray was used.
Than the co-ordinates of target position on screen
were defined by distance and angle. Presently radars
used screen where the picture is projected in raster
scan method. It means that position of targets is po-
sitioned in orthogonal co-ordinates XY. Thus the
target dates achieved from radar sensor is trans-
formed to these systems. The position of target A
has a linear co-ordinate:
X
A
= D∙sin NR (1)
Y
A
= D∙cos NR (2)
where D= distance of target, NR=, bearing of target,
X
A
= linear horizontal co-ordinate, Y
A
= linear verti-
cal co-ordinate.
Figure 1. Real radar screen image with type P display
4 THE ASSESSMENT OF NAVIGATION
BRIDGE OBSERVATION
In navigational practice there is often a need to com-
pare a situation detected by the radar and displayed
on the screen with a situation seen by the human
eye. In this case the perceived image has geometry
than that describing distance relation on a chart.
How a picture observed by the human eye is created
is shown on fig. 2 (Galor W. 2007), where A is an
apparent plane of the image, while the observer’s
eye can be seen on the left side of the diagram. The
object O located at the distance A0 (section a can be
neglected here as very small in comparison to A1)
will be displayed as the point O1. The farther objects
lie, the closer to each other and to the point H their
images are seen, where the point H represents a
point lying far away on the horizon. Therefore,
comparison of the results of the eye perspective ob-
servation with a radar display image in the polar co-
ordinate system calls for the transformation of the
coordinate system. Then further actions can be per-
formed, such as the object identification. From the
navigator this transformation requires the capability
of abstract thinking, which not always is possible,
and is always an extra burden for navigator’s mind,
already loaded with a variety of duties. Besides,
there is a risk that such transformation will be incor-
rect. The importance of this problem gets even
greater if we realize that in practice navigators often
has no time to analyze a situation with a pencil in
their hand; then they make an overall estimation tak-
ing advantage of their experience and knowledge; on
this basis navigational decisions are made. It is im-
portant that this experience is connected with the
situation assessment in the display explained in fig-
ure 2. These factors are often a cause of frequent
wrong interpretations of radar images; this, in turn,
has resulted in a fact that in spite of placing fully op-
erational radars on board ships the number of colli-
sions has not been reduced.
Figure 2. Visual assessment of a situation from the bridge.