57
1 INTRODUCTION
Tropicalcyclone avoidance in shipping by merchant
shipsisaconstantelementofbothoceanandcoastal
navigation. It has a significant influence upon the
economicalandsafetyaspectsofthevoyage.Thekey
decision in tropical cyclone avoidance is the
determining of the moment of the beginning of
av
oidance manoeuvre and the determining of the
correct course and speed with maintaining the
commercialandeconomicviabilityofthevoyage.
By commercial and economic viability of the
voyagethefollowingisunderstood:
1 Minimalization of fuel consumption during the
avoidancemaneuver.
2 Maintaining the voyage schedule. Depending by
thetypeofshippingitisunderstoodas:
maint
ainingthechartererspeedthroughoutthe
voyagetramping,
arrivalatthedestinationportaccordingtothe
charterpartyconditionstramping,
arrival at the destination port within the port
windowregularshipping.
Threetypesofencountersituationsarepossiblein
open(ocean)areas(Wiśniewski&Kaczmarek2012):
1 Opposite courses courses of the ship and the
cyclonedifferby150°to210°.
2 Crossing situation– courses of the ship and the
cyclonecrossatanangleof30°‐90°.
3 Overtakingofthecyclonebytheship.
In each of them a certain type of act
ion (course
alteration,slowingdownorspeedingup)isregarded
asthemosteffectiveone.
Determination of the avoidance maneuver in
coastal and restricted waters is a separate
issue.Withintheareaofthetropicalstormthewindis
veryviolentandtheseasarehighandconfused.Swell
isalsohighandconfused,withseveraldifferentswell
systems, often crossing and int
erfering with each
other.Becauseofthatitisadangerousthreatevento
the biggest and wellfound chips. The danger is
especially enhanced when the ship is caught by the
storminrestrictedorshallowwatersorinthevicinity
of land, without adequat
e room to manoeuvre. It is
recommended to remain all the time no less than
80Nm, however, 250Nm is regarded as the safe
distance.(UK Hydrographic Office, NP100, 2016)
Early and effective action might be essential to
precludeanysuchsituationarising.Thekeydecision
intropi
calcycloneavoidanceisthedeterminingofthe
Tropical Cyclones Avoidance in Ocean Navigation
Safety of Navigation and Some Economical Aspects
M.Szymański&B.Wiśniewski
M
aritimeUniversityofSzczecin,Szczecin,Poland
ABSTRACT:Baseduponthetruevoyagesvarious methods of avoidancemaneuver determinationin ship
cycloneencountersituationswerepresented.Thegoalwastofindtheeconomicallyoptimalsolution(minimum
fuel consumption, maintaining the voyage schedule) while at the same time not to exceed an acceptable
weatherrisklevel.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 12
Number 1
March 2018
DOI:10.12716/1001.12.01.06
58
moment of the beginning of avoidance manoeuvre
and also determining the correct course what might
poseaproblemincoastalandrestrictedwaters.
There are no recommended actions in terms of
efficiency in tropical cyclones avoidance in coastal
and restricted waters with regard to type of
encounter.Vicinityofland,
navigationalhazardsand
obstructions (straits, narrows, shoals and shallow
waters)forcetreatmentofeachsuchcase
individually.Thefollowinggeneralstrategiescan be
identified:
1 Steamingawayfromthecycloneatasafedistance
andwaitingitout.
2 Separationfromthecyclonebyland.
3 Waiting out the cyclone
in port or other place of
refuge.
Inthispaperalltypesofencountersituationswere
discussed and analyzed in the aspects of safety and
seatransporteconomy.Theanalyzesarebasedupon
the true voyages by ships in the regions where
tropicalcyclonescanbeencountered.
2 METHODOLOGY
Thefollowing
toolswereemployed:
ORS(Onboard Routing System) BVS 7.0 Bon
Voyage System 7.0 (Applied Weather
Technologies,2014),
ORS SPOS Fleet Management 7.0.0.1 (Meteo
ConsultBV,2009),
123rule(Holweg,2000),
manualanticollisionplot,
CYKLON programme (Wiśniewski&Kaczmarek
2012)(Wiśniewski2012),
shorebasedweatherroutingrecommendationsby
AWT.
In cases, where data were available, determined
avoidanceactionshadbeenevaluatedwiththeuseof
theweathercoefficientK
1/3inventedbytheauthors.
Weatherdatausedandtheirsources:
the weather data file for ORS BVS containing
weather analysis and prognosis up to 16 days in
advance(AWT),
the weather data file for ORS SPOS containing
weather analysis and prognosis up to 9 days in
advance(SPOS),
EGCforecasts,outlooksandadvisories,
surface pressure analysis and prognosis charts
fromJMA(JapaneseMaritimeAgency),
typhoon prognosis charts from JMA (up to 120
hrswith70%probabilitylevel),
typhoonstrongwindsprognosischartsfromJMA
(upto72hrs),
weatherchartsfromNOAA(NOAA)
Results obtained
were compared. The best
solutions in terms of safety and possibility of route
executionwerechosen.
3 WEATHERCOEFFICIENTK
1/3
Definitionofaweathercoefficientofdifficultyofthe
sea voyage is given in (Wiśniewski, 1991) and in
(Wiśniewski1995).Theseworkscontaindefinitionsof
2weathercoefficientsofdifficulty,weathercoefficient
ofdifficulty1andweathercoefficientofdifficulty2,
based on the maximum wave height in
the whole
voyage (coefficient 1) and a height of wave as
observed by the navigators (coefficient 2) which the
ship would encounter en route in the function of
angle of attack and on a calculated or for each ship
definedsafe/acceptableanddangerouswaveheights.
Definitions of safe/acceptable and dangerous wave
heightsarealsogivenintheseworks.
Forevaluationofasafetylevelofroutes testedin
this article a modified weather coefficient 2 was
adopted (Wiśniewski 1995). The modification lies in
replacing the observed wave height h
c with a
forecasted significant wave height h
1/3. A modified
weather coefficient K
1/3 is given by the following
formula:



1
1/3
1/3
1
K11
i
q
ds
in
d
h
nhq

(1)
where:
h
1/3(q)significantwaveheight(h1/3)forecastedona
givensectionoftrack(h
1/3=1,11hc);
h
c –wave height as observed onboard by the
navigators;
h
d(q)safe/acceptablewaveheight
h
sdangerouswaveheight
α
d=nd/naratioofnumberofcaseswheresignificant
wave heights ere equal or bigger than h
d to a total
numberofobservationsinagivensectorofangle of
waveattack
α
s=ns/naratioofnumberofcaseswheresignificant
wave heights ere equal or bigger than h
s to a total
numberofobservationsinagivensectorofangle of
waveattack
4 RESULTS
4.1 TyphoonSOUDELORrestrictedandcoastalareas
Big (LOA=336m,GT=97500, DWT=71274MT)
postpanamaxcontainershiphasencounteredtyphoon
SOUDELORduringthevoyagefromYantian(China,
ETD: 07.08.2015 0300UTC,) to Vancouver (Canada,
ETA:19.08.2015,2100UTC)in
August2015incoastal
andrestrictedareaoftheTaiwanStraitandnorthern
SouthChinaSea..
Routeasrecommendedbynauticalpublicationsis
shown in Fig. 1 (UK Hydrographic Office NP136
2014).Itwas,however,impossibleto steamalongit.
Immediately after commencment of the voyage the
typhoonSOUDELORwasencountered.It
wasmoving
WNWfromthePhilippineSeaoverTaiwantowards
continentalChinaFig.2.