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:

= D∙sin NR (1)

= D∙cos NR (2)

where D= distance of target, NR=, bearing of target,

= linear horizontal co-ordinate, Y

= 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.

474

5 PERSPECTIVE PRESENTATON

The perspective (called also as type B) shows radar

information to the navigator with such geometry that

he or she has been accustomed to since childhood as

a regular observer, with a produced image similar to

a TV or film picture. This imaging has a rectangular

shape, where the horizontal axis is the bearing axis,

while the vertical axis is the distance axis. Unlike a

typical type P display used for other radiolocation

purposes, the perspective display has a linear gradu-

ation on the horizontal axis, while on the vertical ax-

is the graduation adequately intensifies towards the

horizon Galor W. 2008). The target’s co-ordinations

(D, NR) are transformed on perspective presentation

as:

= D∙ sin NR (3)

= D (4)

In the panoramic display the range and direction

have a rectangular representation. Such arrangement

of the coordinates is often used in various areas in

order to enhance distinguishing small angles, e.g.

radar radiation characteristics at the horizontal cross-

section. The method used for the presentation of a

radar image allows to ‘extending’ the waterway,

which will automatically reduce the useless part of

the image on the screen. Figure 3 depicts a compari-

son of two screens with two different displays of

types P and B. The examples show a situation for the

bow sector covering –30

, +30

areas. Naturally, the

sector can be changed within the 0 – 90

range. The

‘O’ marks heading line, ‘A, B, C’ indicate the dif-

ferent wide canals. It is evident that perspective

presentation gives better relation of water area to to-

tal surface of radar screen.

Figure 4 shows a image of the same situation

converted from P presentation into the type B dis-

play.

Figure 3. The radar screen: type P and B displays

The B display has much other beauty. One of

them is easy and fast to detect of ships changing

course from middle of the canal. In many cases the

ships are going on axis of waterway. It is caused by

hydraulic phenomena as suction by edge of canal

(Projekt badawczy...2009). The B type display per-

mits to fast positioning of ship in relation to the

shore. Fig. 5 presents of such situation. The next

beauty is fact, that the perspective presentation per-

mits too much correction of angle’s differentiation

on the screen. It is correctly visible on fig.5 (right)

for B display. The area near ship’s position is

stretched widely to P display. It highly permits for

identification targets near the ship. Especially it re-

spects the navigational marks (buoys, beacons), wa-

ter structures (locks, bridges) and floating crafts

(boats, yachts).

The above considerations on the method of pre-

senting a situation of a vessel engaged in inland nav-

igation justify the thesis that the method of vessel

position determination (accuracy) and the mode of

situation display are of major importance for naviga-

tors responsible for the process of navigation in in-

land waterways.

Figure 4. The real situation presented on screen radar - P (left) and B (right) displays

475

Figure 5. The presentation of ships course on right and left of axis waterway

6 SUMMMARY

The safety of navigation in restricted waters, particu-

larly inland waterways, depends on the accuracy of

determining the position of a vessel manoeuvring

within such waters.

The radar is one of the devices for position de-

termination. The most common mode of display

showing the present situation on the screen is a pan-

oramic display (bird’s eye view) similar to that of a

navigational chart.

This type of display does not fully satisfy naviga-

tors’ requirements on fairways and rivers, because

the water area perceived is small in relation to the

surrounding land.

These shortcomings can be significantly reduced

by applying a perspective display. Especially this

kind of presentation of radar situation is useful in

narrow water areas like canals, rivers in inland navi-

gation.

The perspective presentation permits too much

correction of angle’s differentiation on the screen.

REFERENCES

Brożyna, J. 1984. Wskaźnik radarowy, Patent No. 48610, Po-

lish Patent Office.

Fedorowski, J. & Galor, W.& Hajduk, J. 1988. Możliwości za-

stosowania wskaźnika radarowego typu B w żegludze pilo-

tażowej i rzecznej. Scientific Bulletin No 14 of Maritime

University in Szczecin, Szczecin.

Galor, W. 2007. Radar perspective display in inland naviga-

tion, Polish Journal of Environmental Studies, Vol. 16, No

6B.

Galor, W. & Galor, A. 2008. The using of radar by sea-river

ships in inland navigation on lower part of Odra river,

Journal of KONES “Powertrain and Transport”, Warsaw,

pp 178-186.

Galor, W. 2008. Transformation of radar presentation for needs

of sea-river navigation. Advances in transport systems te-

lematics, Wydawnictwo Komunikacji i Łacznosci, War-

szawa.

Galor, W. 2009a. The criterion of safety navigation assesment

in sea-river shipping, Marine Navigation and Safety of Sea

Transportation, publ. by CRC Press/Balkema, The Nether-

land.

Galor, W. 2009b. The ‘certain value’ approach to radar situa-

tion presentation in inland shipping. Conference Book

„Word Canal Conference 2009”, Novy Sad, Serbia.

Projekt badawczy MNiSW N N508 3466 33. 2009. Opracowa-

nie szczegółowych wytycznych do zaprojektowania zinte-

growanego mostka nawigacyjnego jednostek w żegludze

morsko- rzecznej. 2009. Sprawozdanie, Akademia Morska

w Gdyni, Gdynia.

U. S. Radar Operational Characteristic of Radar Classified by

Tactical Application. 2006. Department of Navy, Washing-

ton, USA.