275
1 INTRODUCTION
WhatisanExpertSystem?
An Expert System is a computer program that
emulates the decision making ability of a human
expert. The term emulates means that the Expert
Systemsareintendedtoactinallrespectslikehuman
expert.Emulationismuchstrongerthatasimulation,
which is only required to act like the real thi
ng in
somerespects[1].
An Expert System makes extensive use of
specializedknowledgetosolveproblemsatthelevel
ofahumanexpert.Ahumanexpertisapersonwho
hasexperienceinacertainarea.Thatis,theexperthas
knowledge or special skills tha
t are not known or
available to most people. An expert can solve
problemsthatmostpeoplecannotsolveatallorsolve
themmuchmoreefficiently.
TheknowledgeinExpertSystemsystemsmaybe
either expertise or knowledge that is generally
availablefrombooks,magazinesandknowledgeable
persons.
Expert Systems are ca
pable of computational,
qualitative,descriptiveandexplanatoryfunctions.
AnadditionaladvantageofExpertSystemsisthe
easeofuse,inaprocesswhichboilsdowntoa series
of questions and answers between the computer
program and the user, in which the system receives
relevantinformation,notonlyfromtheuserbutalso
from external sources of knowledge, such as
spreadsheets,andothercalculat
iontools[1].
In yacht building, the time required for the
production of an individual boat has got less
importance than a focus on extremely high quality,
providing exceptional comfort and luxury to the
An Expert S
y
stem for Supporting the Design and
Selection of Mechanical Equipment for Recreational
Crafts
T.Gonciarz
ParkerPolandLtd.,Warsaw,Poland
ABSTRACT:ExpertSystemscanbedefinedascomputerprograms, whosemaintaskistosimulate ahuman
expert, usually in a narrow field of expertise. Expert Systems have experienced tremendous growth and
popularitysincetheircommercialintroductionintheearly1970’s.Today,ExpertSystemsareusedinbusiness,
science, engineering, ma
nufacturing and other engineering applications such as planning, scheduling,
diagnosingequipmentfailuresandareusedinalmosteverystageofthemanufacturingprocessandalsoin
medicine and many other fields. Expert Systems belong to the field of artificial intelligence. An intelligent
computerprogramthatusesknowledgeandinferenceprocedurestosolveproblemstha
taredifficultenoughto
requiresignificanthumanexpertiseforthesolution.ThepurposeofthispaperistopresentanExpertSystem
which assists with the design of yachts and supports the selection of mechanical equipment for yachts and
includesknowledgeinthefieldofyachtingengineering.UsingthepresentedExpertSystemreducestheti
me
duringthedesignandproductionpreparationprocess.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 8
Number 2
June 2014
DOI:10.12716/1001.08.02.13
276
owner and his or her guests with state of the art
furnishings and equipment. This equipment will
include electronic and hydraulic systems providing
the ability to control and maneuver the vessel in
adverseconditionswithalittleornostressandwitha
verysmallcrew.
Very often the reputation of the boa
t building
company is the determining factor in setting the
boat’sfinalpriceandproducingtheordertoproceed
withdesigncompletionandconstruction.
A common practice of boat manufacturers is to
select individual items of equipment from
recommendations in catalogs, which may well be
weightedtospecifyallitemstobe“safe”intermsof
strength and power output, but which ma
y also be
unnecessarily heavy and expensive. This has the
potentialforincreasingthefinalcostoftheyacht,and
in some cases such as diesel engines for bringing
about premature failure as a result of excessive low
powerandlowtemperatureoperation.
It is typi
cal for inland yachts that often are used
smalldieselandpetrolengines.
Conversely, selecting under‐sized or under‐
powered components will lead to frequent
breakdowns, early replacements, and in extreme
situations, may endanger the lives and safety of the
peopleonthevessel.
Ya
chtmanufacturingcostsarealsogreatlyaffected
by excessive expenditures for laborto install over‐
sizedequipment,wellintendedtoensurethesafetyof
the yacht and ensure the comfort of its use. A fully
developed Expert System will help to choose,
customize and calculate the required materials and
equipment for safety, comfort and cost control. In
other words, the informat
ion provided by such an
expert system may affect all costs, causing the final
product of the to be much lower while maintaining
the desired comfort and capabilities required in the
completed yacht. In addition, the use of this Expert
Systemwillmea
nthatproductionwillbesmoothand
efficient.
2 ABOUTEXPERTSYSTEMS
An Expert System is a computer program, which
contains knowledge about a specific and usually
narrow field. The system has a capability to solve
problemscomparablewiththatofahumanexpertin
the same field of knowledge – it is a computer
software designed to solve problems tha
t require
specializedknowledge.ExpertSystemsbelongtothe
field of artificial intelligence, which is the study of
issues including fuzzy logic, evolutionary
computation, neural networks, artificial life and
robotics.Artificialintelligenceisabranchofcomputer
science, the object of which is to study the rules of
human beha
vior and intelligence, to create formal
models of that behavior and human thought
processes and, as a result, to create computer
programs that simulate the behavior and intellect of
humans[2].
The starting point to development of the Expert
System is analysis of the process of p
reparation of
production[3].
Themainideaistocreateprograms,which,when
knowledgeandreasoningtechniquesareintroduced,
cangenerateanswers similar tothose that would be
provided by a highly experienced or educated –
experience is nit equal to engineering or design
knowledge human being. In effect
, you will use the
systemtoaccessthehuman expert’sknowledgeand
experiencethroughtheuserinterfaceofthecomputer
orotherdevicerunningtheprogram.Theuserofthis
service asks questions and receives answers and
explanationspresentedinvariousforms,suchas:text,
video,sound,photo,figure,scheme[3].
2.1 AdvantagesofExpertSystems(Whynottotrytolink
thatwithyachtdesign)
Increasedavailabilit
y.Expertiseisavailableonany
suitable computer hardware. An Expert System
can be considered to be a mass production of
expertise.
Reducedcost.Thecostofprovidingexpertiseper
userisgreatlylowered.
Reduced danger. Expert Systems can be used in
environments tha
t may be considered hazardous
toahuman.
Permanent. The expertise is permanent. Unlike
humanexpertswhomightretire,quitordie.(not
fully true‐ equipment and engineering solutions
do have own life and can be replaced by new
products,software needs updating or
conversionsasthecomputerscanfailtowork–
i.ecouldbedeadaswell)
Mult
iple expertise.The knowledge of multiple
experts can be made available to work
simultaneously and continuously on a problem
dayornight.
Increased reliabilit
y. Expert Systems increase
confidencethatthecorrectdecisionwasmadeby
providinga secondopiniontoahumanexpertor
break a tie in case of disagreements by multiple
humanexperts.
Explanation.The Expert System can explicitly
explain in detail the reasoning that led to a
conclusion.Ahumanhoweverma
ybetootired,or
unwillingorunabletodothisallthetime.Thiscan
increase the confidence that the correct decision
wasundertaken.
Fastresponse.Fastorreal‐timeresponsemaybe
necessaryforsomeapplications.dependingonthe
software and hardware used, an Expert System
ma
yrespond faster and is more readily available
thanahumanexpert.
Steady,unemotional,andcompleteresponseatall
times.This may be very important in real time
andemergencysituationswhenahumanmaynot
operate at peak efficiency because of stress or
fatigue.
IntelligentdatabaseExpertSystemscanbeusedto
accessadatabaseinanint
elligentmanner.
Intelligenttutor.TheExpertSystemmayactasan
intelligenttutorbylettingthestudentrunsample
programs and explaining the system’s reasoning
[4].
277
2.2 DisadvantagesofExpertSystems
Answersmaynotalwaysbecorrect.Expertsoften
make mistakes, so it can be expected that Expert
Systems will also make mistakes. These errors
couldbequitecostlyattimes.
Knowledge limited to the domain of expertise.
Expert Systems always endeavor to deduce a
solution,regardlessofwhetherornottheproblem
at hand is within the system’s field of expertise.
Theyhavelimit
edknowledgeofwhattheyknow
and when they know it. As a result of this
misleadingorincorrectanswersmaybegenerated,
which an unsuspecting user may take as fact. A
humanexpert,incontrast,willknowthelimit
sof
theirabilitiesandknowledge,andasaresultthey
will not try to solve problems outside of their
expertise.
Lackofcommonsenseknowledgecanbedifficult
to represent in expert systems. Some measure of
commonsense can be represented but it must be
doneexplicit
ly.
ExpertSystemscanprovideanexcellentapproach
for solving a large class of problems, but each
application must be chosen carefully so this
technologyisappropriatelyapplied[4].
2.3 ExpertSystemsinManufacturing
ExpertSystemshavebeenusedinmanufacturingfor
a wide variety of applicat
ions. Expert Systems have
beenusedinmanufacturingautomationforanumber
of years. The initial systems developed by the
research community or by early adopters of the
technology provided some significant paybacks and
created an initial enthusiasm for the technology.
ExpertSystemshaveagreatdealofopport
unitiesfor
implementation into manufacturing, such as
scheduling and forecasting, simulation, process
modeling, and resource allocation, diagnostics,
process control and planning, quality and safety,
pricing,packaging,andcustomizing.Theseareascan
all be divided up again so there are hundred’s of
possibilitiesoutthereforanytype ofmanufacturing
[5].
3 STRUCTUREANDDESCRIPTIONOFTHE
PRESENTEDEXPERTSYSTEMWHICHCANBE
USEDASASUPPORTOFYACHT
MANUFACTURINGPROCESSES
Recreat
ional craft, to which Expert Systems can be
applied, include sailing yachts, displacement‐hull
motorboatsandplanningmotorboats.
Theinspirationtocreate suchasystemisthefact
that the Polish ma
rket does not contain too much
detailed literature describing problems in design of
yachts,engineeringproductionofyachts.Thereisno
Expert System supporting the yacht design and
manufacturingprocess.Thereisa strongdemandfor
materials presenting practical knowledge in field of
yachtdesignandmanufacturingbutsofar,noExpert
System has been developed in Poland, and perha
ps
the world, to assist in that design and production
process – no yacht designer or manufacturer in
Polandusessuchsoftware.
ThedescribedExpertSystemhasbeenbuiltasan
application of the PC‐Shell computer tool, an
independent tool for constructi
on of Expert Systems
[6].Itcombinesvariousmethodsofsolvingproblems
andknowledgerepresentation.Itcanbeusedinany
field,hencetherangeofitsapplicationsisverywide.
The PC‐Shell is mainly predisposed to solve the
problems of the diagnostic and classification and
interpretationofdata[6].
UsingExpertSystemsboilsdowntothesupplyof
fact
sorotherinformationtotheExpertSystemwhere,
onthisbasis,theexpertanswerispresented[6].
Figure1.SchematicdiagramofthepresentedExpertSystem
3.1 Knowledgebase(yachtdesignandconstruction)
Aknowledgebasecontainsfactsandruleswhichare
necessarytosolvetheprobleminaspecificfield.The
facts are sentences that mean for example: sailing
vessel has a length of 15 meters. This fact can be
representedasarelationshipbetweencertainobjects
andcharact
erizedwithdifferentfeatures.Besidesitin
the knowledge base can be other objects such as
displacementformotorboatsorplanning‐hullpower
boats.
Animportantfeatureofthesystemisthepossible
ofparameterizationoftheknowledgebases.Withthis
solution the dynamic changes of selected va
lues
(parameters) in the knowledge base, take place
without any changes in the source code of the base
[7]. A good example of the application of
parameterization mechanism can be a knowledge
baseinwhichwetestsomevaluesofsomeindicators
such as how to choose the correct bow and stern
thrusterforthevesseldependingonthelengt
hofthe
hull at the water line. At the same time, some
threshold values can be variable, depending on the
case.Forexample,youcanevaluateseveraldifferent
indicatorsofaboatdependingonitsdestination[7].
278
3.2 Database(knowledgesources)
The described Expert System has been built as an
applicationofthePC‐Shell,whichisahybridsystem
ofarrayarchitecture. Withsucha structure,to solve
the problems, it can utilize multiple knowledge
sources[7].
Typical knowledge source in the system of the
array archit
ecture is a knowledge base. In the
presentedExpert System we can useany number of
knowledgesources.
A reference to the sources of knowledge can be
made in the main program (control block) by using
theappropriateinstructions.Itisalsopossibletouse
the same knowledge source by ma
ny different
applicationsthatuseittosolvethesameproblem[7].
The presented Expert System includes sources of
knowledge in the field of engineering yachting. The
program has the following knowledge sources such
us:marinedieselengines,sterngearsystems,exhaust
systems, fuel systems, fresh water systems, waste
water systems, maneuvering systems, hydraulic
steeringsystems,anchoringsystems[7].
3.3 Databasevari
ables
It is an (auxiliary) data base that stores the
conclusions obtained by the system during its
operation. This data base allows you to reconstruct
howinferencesystemworksandpresentittotheuser
(bymeansof)theexplainingmecha
nism[7].
3.4 Editorknowledgebase
This editor allows you to modify the knowledge
containedinthesystem,thankstothis,extensionof
theExpertSystemispossible[7].
3.5 Inferencemechanism
Thetaskoftheinferencemoduleistosolveproblems
byusingtheknowledgecontainedintheknowledge
ba
se. For this purpose we use appropriate inference
procedures. The current version of the system
providesonlybackwardchaining[7].
Backward chaining often takes the form of
verificationofhypotheses,itproceedsfromtherules
tothefacts.Inpractice,thisisdoneinsuchawaythat
thesystemtri
estoagreethehypothesiswithafactor
arule(factstakeprecedence).Iftheyfailtoagreethe
systemsearchesthenextfactortherule,andrepeates
surgery consultation. The system is fitted with are
currence. It provides, inter alia, finding all the
availablesolutionsofacertainproblem[7].
3.6 Explainingmechanism
This mecha
nism allows, at the userʹs request, to
explainwhysuchasystemgavenootheranswer,or
whyasystemaskedyouaspecificquestion
This system provides four kinds of explanations:
“How?ʺ,ʺWhy?ʺ,“Whatitis?ʺandametaphor[7].
3.7 Userinterface
The user uses the system by communicating with it
through the user int
erface, which is used to
communicate with the program. The user asks
questions,providesinformationandreceivesanswers
andexplanations which can be presented in various
forms, such as text, video, audio, image, drawing,
diagram[7,8].
Inaddition,thepresentedsystemincludesmodule
calculat
ions, such as calculation of the theoretical
maximumspeedofthedisplacementhull,thechoice
ofenginepowerfortheboat,thechoiceofwaterlock,
calculationoftheforceactingon the steeringwheel,
thrusterpowerselection,calculationofthemaximum
pullofthewindlass.
4 KNOWLEDGEBASEDESCRIPTIONOFTHE
PRESENTEDEXPERTSYSTEM
ThepresentedExpertSystemdisplaysaknowledgeof
thefollowingsubjects:
1 Calculat
ion of the theoretical maximum speed of
displacementboat
2 Engineandaroundtheengine
the engine power calculator for displacement
boats
theenginepowercalculatorforplanningboa
ts
calculatorforselectionofawaterlock
coolingsystem
fuel system
wetexhaustsystem
engineassembly–Movie
3 Sterngearsystems
constructionofthedriveline
selectionofthediameterofthedriveshaft
selectionofthenumbersofbea
ringssupporting
thedriveshaft
selectionofthetypeofcoupling
4 Transmissions (This part refers to gearboxes and
couplings)
Technodrive(US/German manufacturer of
watercraftdrivesusedalsoinyachts)
ZF(ZFMarineSrl inPadova– pleasurecrafts
eqpmanufacturer)
andmanyothers
5 fresh water system(should include a pota
ble
watersystem–forselectionofdesalinator)
6 wastewatersystem(sanitarywaterpiping)
7 powerhydraulicsteeringsystem
singlesteeringposition
dualsteering position
dualsteering position+autopilot
calculation of the force acting on the rudder
withba
lancesection
calculation of the force acting on the rudder
withoutbalancesection
8 maneuveringsystem
selection of thrusters (bow thruster and stern
thruster)
movie–assemblythrusterinayacht
9 anchoringsystems
selectionoftheweightoftheanchor
selectionofawindlass
Isthereselect
ionofbatterprocedure–vastpartof
equipmentisdrivenbyelectricity)
279
AnExpertSystemisdesignedinsuchawaythatit
iseasy to enter a new source of knowledge into the
system,that is for example, together with the
development of technology, the knowledgeable
engineercanenternewinformationintothesystem.
5 ANEXPERTSYSTEMPRESENTATION
Figure2.TheExpertSystemwelcomescreen
Figure3.MainMenuofdialogbox
InFig.3isaviewtheMainMenufunctions.The
user selects a tab with a problem whose solution is
lookingfor.
Figure4.TheEnginePowerCalculatorofdialogbox
InFig.4 aviewofthefunctionwhichenablesthe
calculationoftherequiredenginepowerfortheboat
is shown. The user selects from the Main Menu
functions ”Engine power calculator” and enters
valuessuchasthelengthandwidthofthehullatthe
water line, draft and
number of engines. After
clicking the Calculate button the required engine
powerfortheboatN
eisreturned.
Figure5.Thewindlassselectioncalculatorofdialogbox
Fig. 5. What pull capability of windlass will I
need?
The only meaningful way to rate anchor winch
performance isby looking at what it will lift and at
whatspeed.Thetwothingstoconsiderare:
themaximumpullcapability
theworkingloadofthewinch
Maximum pull
(sometimes referred to as stall
load) is the maximum short term or instantaneous
pull of the winch. Working load is generally rated
about a third of the maximum pull and is usually
considered to be the load that the winch is pulling
oncetheanchorisoff thebottom.To
determineyour
required maximum pull capability, complete the
calculationabove.Fillin:D–chainwirediameter,L1
– chain length, L2 – rope length, C – weight of the
anchor. And after clicking the Calculate button the
resultisthemaximumpull.
6 ASSESSMENTOFTHEPRESENTEDEXPERT
SYSTEM
The
assessment of the Expert System in terms of its
construction, usefulness, accuracy has been divided
into two stages, through which an objective
evaluationhasbeenmade.
Firststep.Ratingtheknowledgebase.
The knowledge base is the foundation of the
Expert System. It contains facts and rules that are
necessary
to solve the problem in the field.
Knowledge that is stored in the form of rules, was
subjectedtoadetailedassessmentofsixexperts.The
experts assessed the correctness of constructed rules
andstoredfactsintermsofitscontent.
Assessmentbytheexpertsincludedalloftherules
storedintheknowledgebase.
Toobtainhigh‐qualityoftheknowledgebasethey
used the following assumptions. If the rule obtains
lessthan70%oftheaverageofallevaluationsofthe
respondents, then the rule is discarded from the
source of the knowledge and replaced with another
one,that
isalsosubjectedtoevaluation.
280
Secondstep.TheExpertSystemwastestedinthree
independentcompaniesinthemarineindustry.
TheselectedstaffresponsiblefortestingtheExpert
Systemisagroupofexpertsandspecialistswho,ona
daily basis, work in manufacturing, in pre‐
production, and as designers and technicians are
responsible
fortheassemblyprocess.
Responses obtained from the Expert System
werechecked and compared with the professional
literaturebythepeoplewhotestedtheprogram.
The system was found to be a highly useful
programduetoitsfollowingcharacteristics:
easytofindinformation
interfacetransparency
speedof
responses
theprogramincludesextensiveknowledge.
ThetestedExpertSystemhashelpedtoshortenthe
pre‐production phase of the manufacturing process
and resulted in a dramatic reduction in final vessel
costsbyoptimizingtheselectedequipmentpackage.
Ithas made a unique contribution to manufacturing
efficiency.
7 CONCLUSIONS
The Expert System is a comprehensive guide to
engineeringandmanufacturingyachtsapplications.
Emphasizingtheba sic conceptsandprocedures,it
focusesnotonlyonthetechnologybutalsoonhowto
select,initiate,implementandmanageoftechnology.
This Expert System presents guidelines ranging
from problem selection, data analysis, validation,
integration,
implementationandmaintenance.People
whowilluse the presentedExpert Systemcan work
moreefficiently.
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