30 September 2016 1

A Farewell to the Design SpiralA Farewell to the Design Spiral

Horst Nowacki,

Technische Universität Berlin

Invited Note Presented at the

Mini-Symposium on

Ship Design, Ship Hydrodynamics

&Maritime Safety

Athens, September 30, 2016

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ContentsContents

1. Introduction

2. Early History of the Design Spiral

3. Innovation in Ship Design Methodology

4. Modern Concepts of Ship Design

5. Comparison Sequential vs. Concurrent

Engineering

6. Achievements and Contributions

7. Conclusions and Congratulations

References

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1. Introduction1. Introduction

My note will actually combine three farewells:

Farewell to the design spiral

(from sequential to concurrent design)

Farewell to 20th century design methodology

(abandoning single ship viewpoint)

Farewell to Prof. Papanikolaou after more than

30 years of research and teaching at NTUA

(1985-2016)

1. Introduction (cont.)1. Introduction (cont.)

I claim the design spiral is an incomplete,

inflexible, misleading and hence obsolete paradigm

of the design process.

It ought to be replaced by a systems analysis

based, concurrent engineering, team work

oriented paradigm.

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2. Early 2. Early HistoryHistory ofof thethe Design Spiral: Evans (1959) Design Spiral: Evans (1959)

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J. Harvey Evans: 1958, 1959, 1963,

[1] ,[2], [3].

„Optimized Design of Midship

Section“.

Spiral depicts sequential, cyclical

decision process . Purpose: Optimal,

low weight midship section structure.

Basis: Class rules.

At every intersection of a spoke with

a spiral a calculation task is

performed to update the structure.

Result: Low weight, feasible design.

2. Early 2. Early HistoryHistory ofof thethe Design Spiral: Design Spiral: MarAdMarAd (1965) (1965)

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Murphy, Sabat, Taylor,

MarAD, 1965: „Low cost ship

design.“

Scope: Preliminary design

cycles up to reliable cost

estimate.

Sequential, cyclical approach

in rigid sequence.

Univariate systematic

variation with constraints.

Rules based.

Result: Single feasible ship

with lowest building and fuel

cost.

2. Early 2. Early HistoryHistory ofof thethe Design Spiral: BSRADesign Spiral: BSRA

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Hurst, Buxton, BSRA,

1991/92.

Design spiral for

preliminary design up to

shipyard tender.

Elaborate sequence of

design steps. Basis of

software system

BRITSHIPS. Sequential,

cyclical approach with

increasing complexity.

Result: Single feasible ship

with economically reliable

tender.

2. Early 2. Early HistoryHistory ofof thethe Design Spiral: SDC (1980)Design Spiral: SDC (1980)

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Ship Design and Construction,

Kiss, Taggart (1980)

Gale, Lamb (2003)

Both editions drawn from Evans.

Sequential, cyclical approach.

Preliminary design up to contract

design. Subdivision into 4 design

phases.Result: Single feasible design

of low cost. Used in parametric design

studies.

2. Early 2. Early HistoryHistory ofof thethe Design Spiral: Design Spiral: ComparisonComparison

No. Author(s) Date Criterion Scope Basis Objective

1 J.H. Evans [1], [2], [3] 1959 Weight or

Cost Midship Section

Structure Class. rules

Cheapest or lightest

structure

2 MarAd

(Murphy et al.) [4]

1965 Least Cost Prelim. Design Rules Least cost

ship

3 BSRA (Hurst,

Buxton) [5], [6]

1971 RFR, NPV, Tradeoffs

Design up to tender Rules Best tenders

4 SDC (Kiss,

Gale) [7], [8]

1980 Cost Prelim. Design Rules Economic,

feasible design

5 Papanikolaou

[9]

2014 Same as in No. 4 From

rules to goals

Basis for optimization

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Design Spirals

3. Innovation in 3. Innovation in ShipShip Design Design MethodologyMethodology

Innovative Elements:

• Systems Engineering (1950)

• Computer Aided Design (1965)

• Optimization (1965)

• Economization (1967)

• Parametric Design (1970)

• Discretized Analysis Tools (1980)

• Concurrent Engineering (1985)

• Probabilistic Risk Analysis (2000)

• Globalization (2000)

• Open Systems Communication (2000)

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3. Innovation in 3. Innovation in ShipShip Design Design MethodologyMethodology ((contcont.).)

R = Requirements

S = Solution Space

D = Design variables

P = Parameters

M = Measure of merit

C = Constraints

The Systems Approach

4. Modern 4. Modern ConceptsConcepts in in ShipShip DesignDesign

• The Product Model

• The Process Model

• The Concurrent Engineering Approach

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4. Modern 4. Modern ConceptsConcepts in in ShipShip Design: The Design: The ProductProduct ModelModel

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The Product Model contains all the data

describing the ship in its design,

production and potentially operating

phases (Life Cycle Product Model).

The Product Model is built up step by

step by synthesis actions and is

analyzed at each stage by analytical

methods. Thus it is gradually

completed.

The sequence of steps in developing the

product model is in principle arbitrary.

Whenever the information is incomplete

for performing a certain step, it must be

substituted by provisional, assumed or

approximated data. Thus the product

model is open to overlapping

concurrent engineering actions.

4. Modern 4. Modern ConceptsConcepts in in ShipShip Design: The Design: The ProcessProcess ModelModel

The Product Model ought be supplemented by a

Process Model, which describes all the activities

that lead to the completion of the product and

potentially in its operation throughout its life.

The Process Model is formulated in terms of the

network of activities in the product lifecycle or at

least to its delivery. This activity model is

expressed by a set of transactions and events.

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4. 4. Modern Modern ConceptsConcepts in in ShipShip DesignDesign: : ConcurrentConcurrent EngineeringEngineering

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In Concurrent Engineering

the activities of several team

members may deal with

several overlapping phases

simultaneously and need not

await the completion of the

preceding phases. See

Figure. Whenever infor-

mation from other phases is

missing, it may be

substituted by provisional

assumptions and approxi-

mations. This saves time

toward earlier completion.

Earlier product delivery is a

competitive advantage.

On the other hand parallel work on related

design phases requires close control of

mutual dependencies, careful coordination

and good team work. Such close control

causes extra efforts and cost. Thus labor cost

may not diminish.

5. 5. ComparisonComparison ofof SequentialSequential vs. vs. ConcurrentConcurrent Engineering Engineering

Subject Approach ca. 1970 Modern approach

Paradigm Design spiral paradigm Systems paradigm

Sequence Consecutive steps Overlapping design phases

Design process Sequential engineering Concurrent engineering

Responsibilities Single persons, one after another

Several persons in design team

Regulatory basis Rule based design New IMO approach

Design logic Rule based design Goal based design (IMO)

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Trends in Ship Design Methodology (ca. 1970-2016)

5. 5. ComparisonComparison ofof SequentialSequential vs. vs. ConcurrentConcurrent Engineering (Engineering (contcont.).)

Subject Approach ca. 1970 Modern approach

Decision basis Semi-empirical Rational

Uncertainty Treatment Deterministic model Probabilistic model

Treatment of Parameters Several univariate passes Multivariate continuum

Solution search Trial and error Optimization with constraints

Criteria Single objective function and multiple constraints

Multiple measures of merit and constraints

Scope of goals Favorable tender by builder Owner’s life cycle cost

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Trends in Ship Design Methodology (ca. 1970-2016)

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66. Achievements and Contributions. Achievements and Contributions

Ship design in the past three or four decades has experienced

many new achievements. Prof. Papanikolaou and his team at

NTUA have made significant contributions to most of them.

To mention only a few top areas of innovation:

In design methodology:

Economic efficiency (quantification)

Safety and risk assessment (probabilistic models)

Rationality (measures of merit, cause and effect)

Optimality (unified format, multimodality, MCO)

Versatility (greater scope and depth, many new ship types)

Accounting for environmental safety

Risk Based Ship Design

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6. Achievements and 6. Achievements and Contributions (cont.)Contributions (cont.)

In computer technology:

Integration (neutral interfaces)

Open communication (data sharing and exchange)

Longevity (neutral archiving)

Man-machine interaction (simulation, visualization)

Process management (modeling of time depen-

dence, queueing models, process optimization)

Life cycle services (Product Lifecycle Management)

Probabilistic modeling of risks and uncertainties

Simulation and queueing theory

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LiteratureLiterature

1. J. Harvey Evans: “A Structural Analysis and Design Integration with Application to

the Midship Section Characteristics of Transversely Framed Ships”, Trans. SNAME, vol. 66,

1958.

2. J. Harvey Evans: ”Basic Design Concepts“, J. American Society of Naval Engineers,

1959.

3. J. Harvey Evans, D. Khoushy: “Optimimal Design of Midship Section”, Trans.

SNAME, 1963.

4. R. Murphy, D.J. Sabat, R.J. Taylor: “Least Cost Ship Characteristics by Computer

Techniques”, Marine Technology, SNAME, April 1965,

5. R. Hurst: “Advanced Techniques in Ship Design and Construction”, Lloyd’s List,

December 1971.

6. Ian L. Buxton: “Engineering Economics and Ship Design”, British Ship Research

Association, Wallsend, 2nd ed., 1976.

7. Ronald K. Kiss: “Mission Analysis and Basic Design”, 1st ch. in Robert Taggart, ed.,

“Ship Design and Construction”, SNAME, New York, 1980.

8. Peter A. Gale: “The Ship Design Process”, Ch. 5 in Thomas Lamb, ed.: “Ship Design

and Construction”, SNAME, Jersey City, NJ, 2003.

9. Apostolos D. Papanikolaou: “Ship Design”, Springer Science + Business Media,

Dordrecht Heidelberg New York London, 2014.

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7. Conclusions and Congratulations7. Conclusions and Congratulations

Ship design in the course of five decades of computer

use has become more rational, more systematic and

analytical, more transparent in its justifications.

The quality and safety of the product ship have

benefitted from this.

Ships have remained a foundation of global trade and

of worldwide standards of living.

Much work lies ahead of us. The past record of

marine design and Computer Aided Ship Design

encourages us to look confidently ahead at future

challenges to be faced.

77. . CongratulationsCongratulations

Today we are together here to

express our gratitude and

appreciation to Prof.

Papanikolaou, also on behalf

of his colleagues, team mates

and students, for his personal

contributions and his strong

commitment to ship design!

Congratulations and thank

you, Apostolos!

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Computer Aided

Flower (Bézier)

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