531
1 INTRODUCTION
High speed vessels are primarily designed for short
distance services as public transport of passengers
and vehicles. The range of high speed, according to
the Code of highspeed vessels begins at 20 knots,
which depends on the cruise speed you desire for
yourvessel;youwillhavetousethemosta
ppropriate
typeofpropellant.
In general in the past 20 years they have been
building highspeed vessels with speeds above 33
Improving the Efficiency of a High Speed Catamaran
Through the Replacement of the Propulsion System
G.deMelo&I.Echevarrieta
PolytechnicUniversityofCatalonia,Barcelona,Spain
J
.M.Serra
TRASMAPI,ThecnicalManager,Ibiza,Spain
ABSTRACT:Thehighspeedvesselsareprimarilydesignedforshortdistancesservicesaspublictransportof
passengersand vehicles.The rangeof highspeed, accordingto theCode ofhighspeed vesselsbegins at20
knots,whichdependsonthecruisespeedyoudesireforyourvessel;youwillhavetousethemosta
ppropriate
typeofpropellant.
Ingeneral,inthepast20years,theyhavebeenbuildinghighspeedvesselswithspeeds above33knots,which
meantinstallingwaterjetpropellantscoupledtopowerfulenginesandthereforeofhighconsumptionoffuel,
increasingoperatingcostsandcausingincreasedairpollut
ion.
Althoughthepricesoffuelhavebeenreducedtohalf,duetothesharpfallinoil prices,theconsumptionof
fuelandtheairpollutionremainshighatthesespeedsandpowersused,inadditiontothatthereduction
ofthetimespentoneachtri
pisnotexcessive,mainlyinshortroutesthatarelessthananhour.
Thisarticleisaboutadaptingashipofhighspeedservice,withamaximumspeedintestsof34knotsandto
reduceitsoperatingcosts(fuel,maintenance,etc.)andmakeiteconomicallyviable;beforethetra
nsformation,
thisvesselwasoperatingwithaservicespeedof22knots,andwithaconsumptionpermileof135littersof
MGO.
Thetransformationprocesshasconsistedby:
Replacementofthetwooriginalwaterjetwithfourshaftlineswithfixpitchpropeller.
Replacement of thetwooriginalma
in engines (2x6500 kW = 13000 kW) by four engines (4x1380kW=
5.520kW).
Changingtheunderwaterhullshapetofitthenewpropellersandmaximizeitsefficiency.
Relocationofauxiliaryengines,toachievethemostefficienttrim.
Installationoftwolateralpropellerstoimprovemaneuverabilit
yandshortenthetotaltimeofjourney.
Afterthereformandthereturntoserviceofthevesselwithaservicespeedofover22knots,ithasbeenverified
thattheconsumptionpermileisof45littersMGO,representingareductionof65%ofconsumptionandeven
morereductionofemissionsasthenewenginescomplywiththelat
estregulations.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 9
Number 4
December 2015
DOI:10.12716/1001.09.04.09
532
knots, which meant installing water jet propellants
coupled to powerful engines and therefore of high
consumption,increasingoperatingcostsandcausing
increasedairpollution.
Althoughthepricesoffuelhavebeenreducedto
half, due to the sharp fall in oil prices, the
consumptionoffuelandtheairpollution
remains
highatthesespeedsandpowersused,inadditionto
thatthereductionofthetimespentoneachtripisnot
excessive,mainlyinshortroutesthatarelessthanan
hour.
2 TRANSFORMATIONREQUIREMENTS
Trasmapi is a shipping company that has dedicated
morethanthirtyyearsto
thetransportofpassengers
between the islands of Ibiza and Formentera, with
highspeed vessels. In 2013 it was decided to
incorporate to the service the transport of vehicles
thatiswhentheprocessoffindinga unitthat could
satisfytherequirementsbegan:
The journey between Ibiza and La
Savina (11
nauticalmiles)shouldbedoneinlessthan30min.
Thereforetheserviceofspeedwouldhavetobe22
knots.
Thefuelconsumptionshouldbelessthan50lper
milenavigatedandoperationshouldberespectful
withtheenvironment.
Thenavigabilityandmaneuverabilityskills
should
beappropriatetotheroute.
The High Speed Vessel Castaví Jet was found
togetherwithhertwin(hulls54and55)inthesecond
hand market,they were built in the shipyard
Austal Ships Pty Ltd in 1997. It was an aluminum
catamaran used for the transport of passenger and
vehicles.
These catamarans were purchased by the
municipal transport company Istanbul (IDO) and
operatedacrosstheSeaofMarmara,untiltheincrease
offuelmadetheoperationnotviableeconomically.
The original propulsive system consisted in two
diesel engines MTU 20V 1163 TB73L with a total
power capacity of 13,000
kW actuating through two
waterjet,withwhichtheyobtainedamaximumspeed
intestsof34knots,onthecommercialroutebetween
Yenikapi (Istambul) and Yolava it operated at a
servicespeedof22to23knots,wellbelowthedesign,
yet fuel consumption was excessive, as well as the
power
used, operating below 80% MCR, makes the
consumptionincreasessubstantially.
Figure1.Imageofthecatamaranstakenduringtheseatrial
doneinAustralia
3 ANALYSISANDSTUDYOFTHENEW
PROPULSIVESYSTEM
After a detailed technical study we came to the
conclusionthat thewayto meetthe requirementsof
theshippingcompanyTRASMAPIwastopurchase
thehighspeedvesseltypeCastavíJetandmakeitgo
throughatransformationthatbasicallyconsists
in:
Table1.PropulsionChange
_______________________________________________
ItemCurrentProposed
_______________________________________________
MainEngines2xMTU20V 4xMitsubishiS16R
1163engines MPTK
Gearbox 2xReintjes 4xZF5355
VLJ4431
Meansof 2xKaMeWa 4xFixedPitchpropeller
Propulsion 125SIIwaterjets 4xspaderudder
andsteering
_______________________________________________
The proposed conversion will be archived by
addressingthefollowingareas:
1 WeightAnalysis
2 Hullformdevelopment
3 Shaftlinearrangement
4 Regulatoryimpacts
Otheraspectsofthereconfigurationinvolve:
Removal of the existing ride control forward T
Foils,
Relocation of Auxiliary engines (generating sets)
fromauxiliaryengine
roomtomainengineroom
Addition of tunnel side thruster into the ride
controlroomofeachhull.
Replacement of the two original water jet with
fourshaftlineswithfixpitchpropeller.
Replacementofthetwooriginalmainengines(2x
6500 kW = 13000 kW)
with four engines (4 x
1380kW=5.520kW).
Changingtheunderwaterhullshapetofitthenew
propellersandmaximizeitsefficiency.
Relocation of auxiliary engines, to achieve the
mostefficienttrim.
Installation of two lateral propellers to improve
maneuverability and shorten the total time of
journey.
TheextensiveexperienceofTRASMAPI’stechnical
director and the people who design highspeed
vessels have been the main basis for the creation of
thisreformproject.Thefactthattwinboatscouldbe
operated, as it occurs with the Fjellstrand 38.8
catamarans,equipped withwater jetpropulsion and
fix
pitchpropeller,hasallowedustogatherfirsthand
informationto beable todetermine the efficiencyof
thedifferent propulsionsystems in directly
comparablemodelsandatfullscale.
After studying the different propulsion systems,
the most effective for the new service speed of 22
knotswasshownwithfull
submergedpropellerswith
free actuation. For this reason it was decided to
replacetheoriginaljetpropulsionpropellerwiththe
conventionalformat.