International Journal

on Marine Navigation

and Safety of Sea Transportation

Volume 2

Number 4

December 2008

383

Mooring the Ferry m/f “Gryf” in Extreme

Hydro and Meteorological Conditions

A. Kowalski

Unity Line Ltd., Szczecin, Poland

ABSTRACT: The paper introduces some possible manoeuvres of the ferry „Gryf” in difficult hydro and

meteorological conditions, in which standard methods do not permit execution of mooring and unmooring.

Brief characteristics of the ferry m/f „Gryf” have been presented. Typical and most often met extreme hydro

and meteorological conditions have been described for Świnoujście and Ystad. Examplary techniques of

manoeuvres have also been presented for both ports of operation.

1 INTRODUCTION

The ferry m/f “Gryf” left building shipyard in year

1990 as typical ro-ro passenger ship. It was bought

in year 2004 and has been modernized and rebuild.

Since January 2005 being operated by Unity Line

Ltd. M/f “Gryf”, it has been adapted to transport

beyond 100 lorries on three closed decks.

Simultaneously it can also carry passengers together

with cars. Her construction enables shipping without

region’s limits.

The ship has two propellers. Each medium speed

main engine drives one controllable-pitch propeller

trough transmission gear. Behind each of them

double, flap rudders are situated. Both are coupled.

− Ferry main particulars:

− length overall 157, 9 m,

− width 24 m,

− maximum draft 5, 90 m,

− Mm power of main engines 2 x 3960 kW,

− Ms sum of power two bow thrusters 1536 kW,

− area exposed wind pressure near 3 thousand m2.

After comparisons of ferry m/f “Gryf” to ferry

m/f “Polonia” (also property of Unity Line Ltd.,

most modern ferry operated by Polish Ship Owners)

one can name some differences, which have to be

taken into consideration by Captain manoeuvring the

vessel. M/f “Polonia” can navigate practically in

every hydro and meteorological conditions occuring

in her region of operating. M/f “Gryf” possessing

smaller size has unquestionably smaller coefficients

of indicatory power to lengths overall as well to the

area exposed to wind pressure [1].

Experience in manoeuvring the ferry was

assembled on the line Świnoujście-Ystad in years

2005 and 2006. The ferry in Świnoujście is moored

port side on position No 4 of Ferry Terminal. Bow

ramp was laying down on the shore adjustable

platform. In Ystad the ferry was always moored

starboard side at “Polen I” with the stern ramp

ashore.

With a dose of simplification, we can define

regular hydro and meteorological conditions (wind

and current) in which ferry can execute all expected

manoeuvres individually by means of routine setting

of own engines, thrusters and helms.

A good and universal test defining regular

conditions is 360o turning executed in the area of

turning circle. At the beginning and after completion

of the test, the ferry should be stopped in relation to

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the bottom. The initial course of wind should be

around 90o. For obvious reasons it is very difficult

to execute the test in the port’s area and in the real

turn circle area. It is safest to carry out the test for

example in gulfs or in areas sheltered from waves

but not from the wind. The Pilot Navigational

System or an electronic chart in suitable scale have

to be used for registration and for controlling of

execution of manoeuvres. Additional limits for

settings of engines and thrusters can result from the

construction of the bottom and wharfs. Here will be

determine maximum, admissible speed of propeller

stream at the bottom [2].

The aim of this paper is not to determine

the maximum unfavourable conditions in which

manoeuvring is yet possible. The goal of this paper

is to describe techniques used during manoeuvring

of the ferry in extremely difficult hydro and

meteorological conditions.

2 MANOEUVRING OF FERRY M/F “GRYF”

IN PORT ŚWINOUJŚCIE

2.1 Mooring

In typical circumstances the ferry m/f “Gryf” without

turning approaches Terminal stand No 4 parallel to

wharf on course about 208o. The right engine works

astern to slow down runing of the ferry.

Composition of the left engine working forward

together with the rudder adjusted on starboard causes

moment pushing stern to the wharf. Linear speed is

controlled by the engine working astern. Suitable

adjustment of bow thrusters and the main rudder

control transverse speed of approaching the quay by

the ferry. Approximately 20 m from the position of

mooring the ship will be stopped at the fenders.

Then first lines (forward spring and stern line) pass

ashore. The vessel starts shifting forward and during

the running next lines (stern spring and head line)

will be on shore. All options of manoeuvrering in all

extreme weather conditions will be the same from

the first contact with the fenders. Differences will

only occur until this stage.

Ferry Terminal Stand no 4 is relatively well

secured from squally winds. Unfortunately in

Świnoujście river port stormy winds on open waters

accompany changes of water level causing strong

outward and inward currents. Currents speed in

period of collecting empirical data reached

sometimes to 6 knots. It is necessary to realize that

close to stand no 4 rotation of direction and current

speed changes appear. It is caused by advancing the

end of stand into centre line of port channel and also

further deviation of wharf line by as many as 20

degrees in relation to stands 5 and 6. Strong currents

cease in the area about 15 m from the fenders line.

During moorings with strong inward currents it is

necessary to slow down the ferry before reaching

Ferry Terminal It causes serious problems with

keeping the ship on desirable position according to

manoeuvre plan when running with minimum and

steerability speed. Classic approach, parallel to

wharfs causes loss of stern control and it is necessary

to repeat all approach to the quay once again.

In average strong inward currents conditions the

only efficient activity is to approach on courses

deviated into the right from the wharf line direction..

Dependent upon the information about current

conditions received from station VTS Świnoujście,

deviation from course 208

should be out from 10 to

30 degrees to the right. In this manner we obtain

additional moment pushing stern to quay in spite of

comparatively low coefficients of indicatory power

to lengths overall as well to area exposed to wind

pressure.

Fig. 1. Świnoujście mooring with strong inward going currents.

Arrows on stern represents pull direction of both main engines.

Arrow on bow symbolize bow thrusters direction. Vector in a

centre showing shifting direction of the ferry

In these circumstances as a consequence of the

necessitity to continuously stop the ferry with the

right engine and resulting from this weak

possibilities of working forward with left engine, we

obtain an efficient method of “supporting of stern”.

The usage of the above described manoeuvres at

more strong entering currents enforces so heavy

“support of stern” effect, that it will demand

sometimes reversing main engines direction and

also a change of the position of main rudder for

pushing out the stern from wharf. When activity of

current already begins to cease close to the quay, it is

385

necessary to reverse the engine and the rudder again

for pushing the ferry to wharf.

At very strong currents the only solution is to use

the tug and mooring it on stern. The tug will be

ordered to slow down the ferry and if possible to

simultaneously tow at the direction of the. In this

manner the ferry will obtain additional possibility for

“forward” working of main engines. Then the main

rudder will be used in the direction of the quay and

the vessel has big possibility of moving parallel to

the quay.

Not one can give concrete values of currents at

which we decide to approach with stern pushing first

to the wharf. Not one can recognize such power of

entering current during this option of manoeuvre

when it is necessary to reverse the engine and the

rudder to counteract running the stern into the wharf.

These decisions are to be made by the captain under

taking into account his/her experience, unpredictable

direction of currents, gusts, and wind direction that

are at acceptable navigational risk.

Mooring at extremely strong out going current

require continuous control of stern position pushed

by current into the wharf. Turning moment of main

engines should be adjusted to pushing the ferry out

from the quay. At more strongest out going currents

its take into consideration usage of tug moored on

stern.

In certain hydro and meteorological conditions

the risk will be too large to undertake manoeuvres of

mooring. Awaiting for conditions improvement will

be necessary.

2.2 Unmooring

In typical circumstances the ship after dropping

the lines, runs away from wharfs and begins

simultaneous backwards and parallel to quay

movement until the bow passes the end of terminal

stand no 4 (close to shore adjustable platform of the

stand 5). At this moment the ferry begins turning in

the left-hand direction with backward movement

maintained. Manoeuvres of unmooring permit large

relative speed of propellers streams that enable

control of a good position of the ferry stern.

Entering to centre of 310 m turning circle is not

necessary because the length and draft of m/f “Gryf”

permits safe turning in practically all regions of the

port - channel. At stronger out going currents, it is

advisable to change the direction of turning. Then all

manoeuvres instead of drift will be executed in the

turning circle area.

At strong transverse winds one can push the ferry

into wharf with the use of the springs using the

current to move vessel in the direction opposite to

the wind and for reducing the course to the wind.

Fig. 2. Świnoujście unmooring with out going currents. See

comments below figure 1

Ferry Terminal in Świnoujście is relatively well

secured from squally winds. One can even assume

that appearance of any hydro and meteorological

conditions on open sea in of which shipping is safe

for ferry m/f “Gryf” will bring about minimum

safety conditions for unmooring and turning of

the ship.

3 MANOEUVRING OF FERRY M/F “GRYF”

IN PORT YSTAD

3.1 Mooring

During routine manoeuvres the ship enters the port

on course 036

proceeding along the leading marks

line. When the stern passes the right head of internal

breakwater together with lineal movement forward,

the ferry begins turning left, in order to clear of

“Revhuskajen” corner with stern from a distance of

about 25 m.

Continuing turning left of the vessel, from this

moment ferry can begin also astern linear motion

proceed along to quay “Polen I”. Course of the wharf

is 263°. Mooring with starboard. Currents in internal

port do not exist.

At extremely strong SW winds during turning the

ferry should keep away form “Polen I”. The idea is

to create possible large area for strong wind drift and

time for turning the ferry to wharf course. All ferry

captain’s activities at circulation of wind from

directions SW and S are directed at reaching the

quay fenders with minimum energy, best with zero

longitudinal speed of the ferry.

386

The situation is much more difficult when

mooring is accompanied by winds from N - NE

directions. In such situations it is necessary to move

ferry so close to the corner of “Pollen I” that it is

possible to passing any line from bow to the corner

of the quay. Then after transferring ship’s point of

turning forward, and with the same power on stern

we have more profitable ferry turning moment.

Dependent upon the force of wind when approaching

to quay, passing the first line does not have to occur

in the same moment when ferry is parallel to wharfs.

The act of passing the line can be more effective

when the ship is during turning closer to the

northerly courses, when the course to the wind is

lower.

3.2 Unmooring

Routine departure of the ferry means proceeding

with bow thruster pushing the bow into the left

direction and simultaneously very slowly

accelerating the ship. The stern should be held at

constant, safe distance from wharf by use of main

engines settings and the rudder. After passing the

right side internal breakwater, the speed of the ferry

should be strongly accelerated to obtain appropriate

course stability.

With strong winds pushing back from quay,

unmooring proceeds similarly to routine manoeuvre.

Activities should counteract drift caused by the

wind.

Fig. 3. Ystad unmooring with out going wind direction. Left

engine stopped. See comments below figure 1

In the final phase after turning by bow thrusters,

the ferry has to be accelerated a little earlier to

oppose drift done by the wind. Safety of manoeuvre

is emphasized by the fact that between heads of the

internal and external breakwaters on eastern side

there is a wider fairway . That creates more space for

unexpectable drift.

It is considerably more difficult to manoeuvre the

ferry during strong winds pushing ferry to the quay.

Captain’s activity should aim at shifting the point of

turning closer to the stern and to as quick as as

possible diminution of courses to the wind. In such

as situation while working with bow thrusters on

pushing out, it is necessary to choose ship stern area

safe point of support at the quay. Stern spring may

be left on bollard. Operations with main engines and

rudder settings intended to push back the stern and

dropping the stern spring line should be carried out

to obtain lowest possible course to the wind. In this

situation the ferry should have full controllable

manoeuvres on forward and stern. After passing the

line of right side internal breakwater the ferry should

continue moving to the left to obtain suitable spare

height and then the speed has to be strongly

accelerated to obtain good course stability.

4 CONCLUSIONS

Liner trade shipping, and in especially ferry trade

enforces on time sailings to the ports. Usage of other

than routine methods of manoeuvring permits

increasing safety and regularity of shipping which

improves economic results.

It is captain’s experience in manoeuvre, his/her

constant estimation of navigational risk and based on

this making the right decisions has crucial influence

on correct operation of ferry has. One can conclude

based on the presented examples of solving the

mooring problems results that one of the manners of

enlarging abilities of ferries manoeuvre, except

direct enlarging power of engines and bow thrusters,

enlarge experience of captains and using other than

routine manoeuvring manners. This can be achieved

in many ways depending upon different strategies of

crew qualifications improvement.

REFERENCES

[1] Gucma S., Kowalski A., Doświadczalna metoda oceny

zdolności manewrowych cumowania promów morskich.

International Conference „The Role of Navigation I Support

of Human Activity at Sea – NAVSUP 2006”, Gdynia 2006.

[2] Gucma S., Instrukcja eksploatacji stanowiska Nr 4, 5

i 6 Bazy Promów Morskich w Świnoujściu, Maritime

University, Szczecin 2005