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Optimization of the Preliminary Designand Cost Evaluation of Fishing Vessels

Apostolos Papanikolaou, Elas Kariambas, National Technical University of A thens 1

1. Introduction

Our compllter-aided system for preliminary design and cost evalllation of medim-size fish-ing vessels Papanikolaou et .1989,1991) compared the finally selected vessel (a feasible ,not necessarily optimal ] with a statistically mean vessel (based available data databases) . We compared costs, assming the two vessels were otherwise of eqllal

technical design characteristics (owner's reqirements , design criteria and constraints) . Now,an additional formal optimization enables the preliminary design and cost evalllation

of optimized medim-size fishery vessels L OA : 10m -;-28m).

~. Optimization Procedure

The independent variables , parameters, constraints , and criteria have to be defined first. .interactive PC program allows llser-specified starting vallles and bonds differing from defallt (Table 1). However, violation of the given limits for the design variables to a certain

degree can lead to significant errors.

Table : Design variables and constraints with st andard bonds

Design Variable Lower Upper Constraint Lower UpperBond Bond

Overalllength m 10 30 FHV aclieved/reqired 1 .0 1 .3Overalllength/width 3 4 .5 Freeboard achieved/req ired 1 .0 1 .2width/depth 1 .75 2 .15 GM achieved/reqired 1 .0 1.2

prismatic coefficient 0 .55 0 .75 width / d raft 2.0 4 .5

The parameters of the problem are divided into two categories:

Technical Economical cost (detailed approx.) costInflation rateNmber of trips per yearFtel costCrew salaries verage lltilization of fishllOld capacity

verage fish priceDuration of economical life of the vesselVallle of vessel at end of i ts economical lifeBank interestSllbsidy vallleLoan vallleWay of acqittance of the loanLoan interest

Parameters can be llser-specified or defallts from set databases (e.g. the standard mainengine is assmed to be ofhigh-speed type, the standard economicallife of the vessel is 25 years).

Type (trawler , se iner, mixed)Construction material (steel, wood , GRP)Fishhold (FHV) m 3 Speed free rn condition (kn)Towing speed (kn)Range daysRange sm (free rn)

Range sm (towing condition)Crew accommodatedType of main engine (medilm , high speed) mber of main enginesWeight of nets (kp)Weight of fishing eqipment (tons)Refrigeration type

lDept . of & , Heroon Polytecl1l1ion, Zografon , GR-15773 Atllens, Gr eece

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- - - - - - -

-

.. . : : : : :- :. f. ICH IN

: ACcOMODAnor-:: /. LOC~ ~ \ - - - .__:: ~

: f1SII 1I0LrJ - , _. , w.~ H N y.~ . __ . __ . . ._'_' ' ;

- - - - _ __ _ . _ ~ - :~ ~~ - -

Fig. 1: Typical stern trawler arrangement for design al gorithm

FISI NP DATA FILB -- ECONOMICAL CHARACTERISTICS--.Calcu ation method of the construction cost : 1

GENERAL DATA - ...Manhour cost [thous.Drs Ih]: 3 000: AGIOS_NIKOLAOS . . Inflation coefficient from 1991 to now : 1.300

.. .Numb er of trips p er ye ar : 13...Fue l price [DrsIton] : 80000 .

...Sa a ries [Drsfmonth] : 140000.

...M ean fishhold ful1ness : 0 .600

...Mean fi sh pric e [DrsIKg~ 1200... .Durati o n of economical ife of e ss e [years~ 25...Scrap alue of e ssel [thou s.Drs]: 0 .00...Bank interest [ ] 16.00...Subsidy 0.00...Loan 80 .00.. .Way o f acquitanc e of loan 3.. .Total duration of loan [years] : 15.. .Loan interest [ ] 0.00.. .Way of acquit ance of lo an two p arts 3.. .Percentage of loan that corre sponds to

the short term part [ ] : 50 .00...Duration of 1st part [years] : 5...Interest of 1 st par t [ ] 22.00.. Intere st o f 2nd part [ ] 14.00...Grace p eriod [years]: 3

...Name of ship

--- TECHNICAL CHARACTERISTICS ---_ Type of es se l (trawler) : 1...Construction material (steel) : 1.. .Fishhold Volume [m3] 45 .00.. .Speed (free run) [ ] 9.00...Towing Speed [ ] 3 .00...Range (days) 13.0...Range (free run) [sm] 0.0...Range (towing condition) [sm] 0 .0.. .Crew 9...Type of main engine 1.. .Weight of nets [Kg] : 1000.0...R efrigera tion type 1...Weight of fishing equipm ent [tons]: 1.800

Fig. 2 : Typ ical input fle

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Fig. 2 shows a typical set of input parameters. Constraints stem from statutory regulations(minimlun freeboard and minimum metacentric height), and owner's requirements concerningthe vessel size (fishhold volume). Their bounds are also nser-specified or default valnes, Table. The criteria leading to the objective fnction are economical: constrnction/ acquisition costor Net Present Valne Index ( ) or a weighted combination of both. The nser defmesthe weight-coefficients wl resp. W2 for the cost and the The valnes ofthe independent variables , constraints, and objective function must be the same order ofmagnitnde forthe correct application of this multiple-objective optimization method. Theweight coefficients , mnst be of snch magnitnde that the resulting valne of the objectiveflmction is the same order of magnitnde as for the other attribntes, namely of the order one.Thus, the resulting values of the objective fnction will depend the ratio Wl/W2 of thesecoefficients. For Wl/W2 ~ 1 the vessel is optimized with respect to the constrnction cost only;for small Wl/W2 ~ 1 the vessel optimized with respect to the only .

For the optimization we n ,sed the Generalized Rednced Gradient (GRG) method L sdon nd W ren 1986), an originally linear optimization method. Thongh uses linear or linearizedconstraints, allows also nonlinear objective fnctions and nonlinear constraints, as given here.The standard problem solved by the GRG method is :

Minimize:

Subject to:f x

h., x = L< x

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RBSULTS OF PROGRAM FlSH FOR

WEIGHTS

--- DIMENSIONS ---...Oerall Length [m] : 19.46...Waterline Length [m] : 16.63...Length between Perpendiculars [m]: 16.22...Maximum Breadth [m] : 5.25 Depth [ ] : 2 66

_Draft [m] : 1.83...Freeboard [m] : 0.58------ FORM COEFFICIENTS --

...CB : 0.490

...CP : 0.622

...CWL : 0.757--- POWERING ---

...Propeller Diameter [m] : 1.20

...Expanded surface ratio / :0.65

...Number of blades : 3

...Shaft s draft [m] : 1.20

...Number of propellers : 1

.Shaft's effectie coefficient : 0.98

... P/D of propeller : 0.84 SH P f ree r un [PS] : 34 ...RPM of propeller (free run) : 370 .

... propeller caitation (free run) : 0.0...Pull force [ ] : 1508.

...SHP (towing condition) [PS] : 108.

...RPM of propeller ( towing condition) : 297.. caitation of propeller (towing cond.) : 3 .7...Speed (free run) [ ] : 9.00...Speed (towing condition) [ ] : 3 .00... [PS] : 137..Power of electric motors [PS] : 13.7

------- VOLUMES AREAS ---...Accommodati on (required) [mA2} 28.8...Machinery room (required) [m'Z } 7.0...Fuel (required) [m A3]: 7.7...Fresh Water (required) [m A3} 5.6...Fishhold Volume [m A3~ 46.8

...Fish & Ice [] 15 .12

...Fuel Lub. oil [] 6.58

...Fresh Water [] 5 .62

...Proisions [] 0.42

...Steel construction [] 31.49

...Outfit [] 4.42

.Machinery []; 4.23

...Light Ship [tons] : 40.14

...Nets [] 1.0

...Fishing Equipment [] 1. 80

...Crew [tons]: 0.81

...Displacement (qeometric) [] 81.01

...Displacement (weights) [] 81.01------ STABILITY ------

...Condition 1 (10 con sumables 100 fish)

...Centre of Buoyancy [m] : 1.12

...Metacentric radius [m] : 1.50

...Centre of graity [m] : 1.52...Metacentric height [m] : l.11

...Condition 2 (100 consumables 100 fish)

...Centre of Bu oyancy [m] : 1.22

...Metacentric radius [m] : 1.37

...Centre of graity [m] : 1.51

...Metacentric height GM [m] : 1.08

-- C S S (Values thousands DRS) --Steel Structure : Manhours : 3915 .-------- Labor cost :11746

Material cost : 7384. Outfit :Manhours

Labor costMaterial cost

: 503.

: 1508.:24594.

Machinery :ManhoursLabor cost

Material cost

: 639.: 1917:19995.

Cost.s per category : Steel construction---Outfit

MachineryFishing EquipmentGeneral expenses

:19130:26101.:21912: 4700.: 3592.

_ _Total construction cost : 75435 .7

Annual Operational co sts

Fuel : 4648.Lubrication : 232.Salaries :15120Maintenance Repair of Fishing Equipment : 1551.Maintenance Repair of Main Engine : 1315Maintenance Repair of essel : 1357.

Total Maintenance & R epair costs : 4223. _ _ _

InsuranceUnfore seen expen ses

: 1509.: 257.

Total Annual Operation Costs :25990.

Annual Costs : 70762 _ _

PRESENT VALUE :149415.

Net Present Value Index (before Tax) : 1.981Annual Income for zero Net Present Value: 46256.

Required fish weiht (tons ) for NetPresent Value gien its aerage price (Drs/kg) : Pe r Trip: 2.972. Per Day : 0.233. Per ear: 38.55

Required averase price of fish (Drs/kg) for theactual fsh weight (tons) per trip and for NetPresent Value for arying fshhold ful lness :

Fishhold Ful1ness verage Price of Fish

0.30.40.50.60.70.80.91.0

1568.841176.63

941.30784.42672.36588.32522.95470.65

Fig . 3: Typical output file

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the optimization procedure( see Table 1). Start values of these variables are taken from a sta-tistically mean vessel according to the formulated databases. The remaining characteristicsof the ship LBP CB etc.) can be estimated by empirical formulas based existing vessels.The calm-water resistance is estimated by the Ridgely-Nevitt (1967) method for trawlers andDoust's method Traung 1967) or Antoniou's method Antoniou 1969) for seiners and mixedfishery vessels. Wageningen-B propeller is then selected by an algorithm of Politis 1991) .

The available (achieved) fishhold volume can be estimated considering the totally availableunder-deck volume minus the spaces for engine room , accommodation , fuel, water, and ballasttanks . Later the ach ieved fishhold volume is compared with the owner 's specifications allow-ing a margin of 20% the upper limit (see Table 1) . Weights and centers of gravities areestimated in separate groups , namely steel , machinery, outfitting, fuel, lubrication , fresh water, crew, provisions, and finally fish and ice. For the consumables two loadingconditions are considered: 'arrival at port' (design draft, 10% , 100% fish) and'maximum draft' (100% conslmables, 100% fish). stability analysis gives the metacentricheights for the two loading conditions. These values are checked against s afety regulations.The output contains the design characteristics and cost data for the optimal vessel , Fig. 3. additional output set concerns the optimization procedure itself and contains specific data

for the number of iterations performed, the change of values of variables and constraints etc.Table gives for a trawler described by Fig. 2.

Table : Comparison of acq sition cost for an existing and an optimized trawler

Cons truction materia lCrew [persons]Overalllength [m]Length between perpendiclIars [m]Width [m]Depth [m]

Draft [m]Hull coefficientPrismatic coefficientWaterline coefficientSpeed free run condition [kn]Break horsepower [ ]FiShhOld volume achieved [m 3 ]Steel construc tion cost [1000 drs.]Outfit cost [1000 drs.]Machinery cost [1000 drs .]Fishing equipment cost [1000 drs .]General expenses [1000 drs .]Total acqsition cost [1000 drs .]

Exi sting Shipsteel

729.9524 .966.41

4 .22

2.950.5000.6210.75311.00505

148.277692324874637910959

8376175893

Optimized Shipsteel

726.7122 .266 .953.23

2 .280.475

0.5980.73411 .00550

148.1494 8527534497208872

6 781142 392

4 Parametric Analysis

systematic parametric approach to the problem allows some in sight int o t he b ehaviourof the used objective functions ne ar the optimal solutions. D uring th is p roc edur e t he pr obl emparameters were kept fixed . For every r two of the four s e lecte d de sign v aria bl es vari ed sy s-te matically , w hereas the other two r em ained fi xed. Th e o bject iv e ftm ction s pa rticul ar sampl eruns were normalized acq uisition-c onstructi on cos t ( F ig. 4 ), nor ma lized ann a op erat io nal c ost(Fig. 5), and Net Present Va le Index (Fig . 6 ). In all cases, the obj ective fun ctions h ad theiro p tirna. a.longthc bo u nd a ri e s of th e gr a ph s , i .e . op tirna w er e set b y the de si g n co n stl aints _ TnP.

peciar behaviour of the graph s for LO A = 15m is de to the change o f the as snm ed st an-

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Acquisition Cost = F Loa .L/Bdrs/10 8 )

a m / 1000. 10 0.12 0 .14 0.16 0.18 0 .20 0 .22 0.24 0 .26 0.28 0.30 FHV 4 5 m3

VFREE 9 kn0. 44 0.4 4 RANGE 13 days

2CP 0.60 .4 2 0.42

0. 40 0.40

......... .38 0 .38