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SSC-222

CATAMARANS-TECHNOLOGICAL TO SIZE AND APPRAISAL DESIGN INFORMATION

This document for

public

OF STRUCTURAL

AND PROCEDURES

has

been

approved

release

and

sale;

distribution

LIMITS

its

is unlimited.

SHIP STRUCTURE COMMITTEE 1971

/.

.——

——— -.—---- ---

—-

..

SHIP

STRUCTURE AN INTERAGENCY COMMITTEE DEDICATED THE STRUCTURE

COMMITTEE ADVISORY TO IMPROVING OF SHIPS

MEMBER AGENCIES:

ADDRESS CORRESPONDENCE

UNITED STATES COAST GUARD NAVAL. SHIP SYSTEMS COMMAND

SECRETARY

MILITARY SEALIFT COMMAND MARITIME ADMINISTRATION AMERICAN BUREAU OF SHIPPING

U.S. COAST GUARD HEADCIUARTERS WASHINGTON, D.C. 20594 20590

TO:

SHIP SIRUCTURE COMMITTEE

SR 192 1971

The Ship Structure Committee has completed a project that assesses the present state of the art for designing Catamarans, large platform, twin hulled ships. The purpose of the project was to collect and analyze design techniques and data presently available and assess their usefulness for catamarans approaching 1000 feet in length. This report contains procedure for the initial design of a large catamaran and indicates where additional tests should be made before the final design stage is completed.

W. l?. REA III Rear Admiral U.S. Coast Guard Chairman, Ship Structure Committee

—————

.

—’

SSC-222

Final Report on Project SR-192, “Catamaran Designs” to the Ship Structure Committee

CATAMARANS - TECHNOLOGICAL LIMITS TO SIZE AND APPRAISAL OF STRUCTURAL DESIGN INFORMATION AND PROCEDURES

by Naresh M. Maniar and Wei P. Chiang M. Rosenblatt & Son, Inc.

under Department of the Navy Naval Ship Engineering Center Contract No. NOO024-70-C-5145

This doeuvwnt haz been approved for public ?elease and sale; its distribution is unlimited.

U. S. Coast Guard Headquarters Washington, D. C. 1971

-.

ABSTRACT

Existing United States shipbuilding facilities can handle 1000foot catamarans with up to 140-foot individual hull beams on the premise that the hulls would be joined afloat. Major harbors and channels of the world suggest an overall beam limit of 400 feet and 35-foot draft. Drydocking for catamarans over 140-foot in breadth will require new faciliScantlings of a ties or extensive modification to existing facilities. 1000-foot catamaran cargo liner can be expected to be within current shipbuilding capabilities. The uniqueness of the catamaran design lies in the cross-structure and the important facets of the cross-structure design are the prediction of the wave-induced loads and the method of structural analysis. The primary loads are the transverse vertical bendDesigners have reing moments, axial force, shear, and torsion moment~. lied heavily on model tests to obtain design loads and have used general structures principles and individual ingenuity to perform the structural analysis in the absence of established guidelines. Simple semi-empirical equations are proposed for predicting maximum primary loads. A structural analysis method such as the one proposed by Lankford may be employed for conceptual design purposes. The Lankford method assumes the hulls to be rigid and the cross-structure loads to be absorbed by a group of bulkheads and associated effective deck plating. This procetransverse dure in general should provide an overall conservative design and not necessarily an economic or optimized design. Additional research and development work including systematic model test programs are necessary for accumulating additional knowledge in areas of uncertainty and for the establishment of reliable design methods for catamaran structure.

ii

CONTENTS Page INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . ...1 ANALYSIS OF FEATURES THAT MAY IMPOSE SIZE LIMITS . . . . . . . . 2 EXISTING STRUCTURAL DESIGN METHODS 3.1 3.2 3.3

GENERAL. . . . . . . . . . . . . . . . . . . . . . . .4 CROSS-STRUCTURE LOADS . . . . . . . . . . . . . . . . . 4 SURVEY OF EXISTING DESIGN METHODS . . . . . . . . . . . 7

MODEL TEST DATA ANALYSIS 4.1 4.2 4.3

. . . . . . . . . . . . . . . 4

. . . . . . . . . . . . . . . . . . . .17

TEST BACKGROUND . . . . . . . . . . . . . . . . . ...17 DATA CONSOLIDATION AND COMPARISON . . . . . . . . . . .21 DISCUSSION OF THE PLOTS . . . . . . . . . . . . . . . .26

CONDITION FOR MAXIMUM RESPONSE AND RECOMMENDED METHOD FOR DESIGN LOADS ESTIMATE . . . . . . . . . . . . . . . .27 5.1 5.2 5.3 5.4

CONDITION FOR MAXIMUM RESPONSE IN BEAM SEAS DEVELOPMENT OF DESIGN LOAD EQUATIONS. . . . COMPARISON OF LOADS CALCULATED BY PROPOSED EQUATIONS AND BY OTHER METHOD . . . . . . . METHOD FOR DESIGN LOADS ESTIMATE. . . . . .

HULL FLEXIBILITY AND CROSS-STRUCTURE STRESSES.

. . . . . .27 . . . . . .30 . . . . . .35 . . . . . .35

. . . . . . . . .38

DESIGN SHIP. . . . . . . . . . . . . . . . . . . . . . . . . . .40 7.1 7.2 7.3

7.4 7.5

PURPOSE. . . . . . . . . DESIGN DESCRIPTION. . . . EXPLANATION FOR EFFECTIVE CROSS-STRUCTURE LOADS AND DESIGN CONCLUSIONS. . . .

. . . . . . . . . . STRUCTURE STRESSES. . . . . .

. . . . .

. , . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

.40 .43

,43 .45 .45

TOPICS FOR FUTURE RESEARCH AND DEVELOPMENT PROGRAM . . . . . . .47 CONCLUSIONS. . . . . . . . ., ACKNOWLEDGEMENTS.

. . . . . . . . . . . . . . . . .50

. . . . . . . . . . . . . . . , , . . . . , .50

REFERENCES.

. . . . . . . . . . . . . . . . . . . . . . . . . .52

APPENDICES.

. . . . . . . . . . . . . . . . . . . . . . . . . .

1. 2.

3.

CATAMARAN RESISTANCE . . . . . . . . . . . . . . . . . .54 REPRODUCTION OF PORTIONS OF REFERENCE (8), THE STRLICTURAL DESIGN OF THE ASR CATAMARAN CROSS-STRUCTURE” BY BENJAMINW. LANKFORD, JR. . . . . . . . . . .56 REPRODUCTION OF “SUMMARY AND DISCUSSION” OF REF~R: . . ENCE (13), “AMETHOD FOR ESTIMATING LOADS ON CATAMARAN CROSS-STRUCTURE” BY A. L. DISENBACHER, . . . .62

iii

-—,

—

LIST (IFTABLES Table

Page

1

CATAMARAN LOAD AND STRUCTURE ANALYSIS . , . . . . . . . . . . 7

2

PROTOTYPE CHARACTERISTICS OF MODEL TEST VESSELS . . . . . . .19

3

PARTICULARS OF “E. W. THORNTO~l” SERIES SHIPS. . . . . . . . .20

4

PARTICULARS OF “ASR” SERIES SHIPS . . . . . . . . . . . . . .20

5

PARTICULARS OF THE UNIVERSITY OF MIAMI SERIES SHIPS . . . . .20

6

RATIOS OF MAXIMUM LOADS IN BEAM SEAS AND OBLIQUE SEAS . . . .25

7

WAVE-INDUCED TRANSVERSE VERTICAL BENDING MOMENTS IN BEAMSEAS. . . . . . . . . . . . . . . . . . . . . . . . . .36

8

WAVE-INDUCED SHEAR IN BEAM SEAS . . . . . . . . . . . . . . .36

9

WAVE-INDUCED TORSION MOMENT IN OBLIQUE SEAS . . . . . . . . .36

10

DESIGN LOAD SCHEDULE . . . . . . . . . . . . . . . . . . . . .37

11

T-AGOR16 CATAMARAN STRESS SUMMARY . . . . . . . . . . . . . .40

12

DESIGN SHIP PARTICULARS . . . . ... . . . . . . . . . . . . .41

13

DESIGN SHIP WAVE-INDUCED CROSS-STRUCTURE LOADS. . . . . . . .46

14

DESIGN SHIP, CROSS-STRUCTURE STRESS SUMMARY . . . . . . . . .47

iv

LIST OF FIGURES Figure 1 2

Paae CATAMARAN RESPONSE IN A REGULAR BEAM SEA . . . . . . . . . . 15 M *VERSLIS M

3 *

VERSUS L, BEAM SEAS . . . . . . . . . . . . ...23 M

4

VERSUS b3 BEAM SEAS . . . . . . . . . . . . ...23

* 5

F VERSUS A, BEAM SEAS . . . . ... . . . . . . ...23

A;; 6

7 8 9

A, BEAM SEAS . . . . . . . . . . . . ...23

F

so

Ab Zmcw

VERSUS A, BEAM SEAS . . . . . . . . . . . . ...24

To/T1

VERSUS A, OBLIQUE SEAS....

VERSUS AL, OBLIQUE SEAS. . . . . . . . . . . . . 24 ADDED MASS FOR SWAY DIRECTION, SERIES 60, FROM REFERENCE ... . . . . . . . . . . . ... . . . . ...25

10

CATAMARAN IN BEAM WAVES OF DIFFERENT LENGTH. . . . . . . . . 28

11

LOADING CONDITION FOR MAXIMUM VERTICAL BENDI!JG MOMENT INBEAMSEAS. . . . . . . . . . . . . . . . . . . . .30

12

T-AGOR16 STRUCTURAL CO!iFIGURATION. . . ... . . . . . . . . . 39

13

STRUCTURAL MODEL OF T-AGOR16 FOR IBM-1130 “STRESS’’pROGRAM. . . . . . . . . , . . . . . . . . . . . .3g

14

DESIGN SHIP PROFILEANDPLAN.

15

DESIGN SHIP TYPICAL BULKHEAD STRUCTURE . . . . . . . . . ... 42

16

DESIGN SHIP SECTION MODUL1 . . . , . . . . . . . . . . , . . 44

. . . . . . . . . . . . . . . 42

v

.“..

. . . . . . ...24

SHIP STRUCTURE COMMITTEE The SHIP STRUCTURE COMMITTEE is constituted to prosecute a research program to imprmm the hull structures of ships by an extension of knowledge pertaining to design, materials and methods of fabrication. RADM W. F. Rea, III, USCG, Chairman Chief, Office ofhlerchant Marine Safety U. S. Coast Guard Headquarters Mr. E. S. Dillon Chief Office of Ship Construction Maritime Administration

Capt. J. E. Rasmussen, USN Naval Ship Engineering Center Prince Georges Center Capt. L. L. Jackson, USN Maintenance and Repair Officer Military Sealift Command

Mr. K. Morland, Vice President American Bureau of Shipping

SHIP STRUCTURE SUBCOMMITTEE The SHIP STRUCTURE SUBCOMMITTEE acts for the Ship Structure Committee on technical matters by providing technical coordination for the determination of goals and objectives of the program, and by evaluating and interpreting the results in terms of ship structural design, construction and operation. YAVAL SHIP ENGINEERING CENTER

U. S. COAST GUARD

Mr. Mr. Mr. Mr. Mr.

LCDR C. S. Loosmore, USCG - Secretary CDR C. R. Thompson, USCG - Member CDR J. W. Kime, USCG -Alternate CDR J. L. Coburn, USCG - Alternate

P. J. G. H. I.

M. Palermo - Chairman B. O’Brien - Contract Administrator Sorkin - Member S. Sayre - Alternate Fioriti - Alternate

NATIONAL ACADEMY OF SCIENCES MARITIME ADMINISTRATION Mr. Mr. Mr. Mr.

F. A. R. R.

Mr. R. W. Rumke, Liaison Prof. R. A. Yagle, Liaison

Da.shnaw- Member Maillar - Member Falls - Alternate F. Coombs - Alternate

SOCIETY OF NAVAL ARCHITECTS & MARINE ENGINEERS Mr. T. M. Buermann, Liaison

AMERICAN BUREAU OF SHIPPING Mr. S. G. Stiansen - Member Mr. F. J. Crum - Member OFFICE OF NAVAL RESEARCH

BRITISH NAVY STAFF

Mr. J. M. Crowley - Member Or. W. G. Rauch - Alternate NAVAL SHIP RESEARCH & DEVELOPMENT CENTER

Dr. V. Flint, Liaison CDR P. H. H. Ablett, RCNC, Liaison

Mr. A. B. Stavovy - Alternate WELDING RESEARCH COUNCIL MILITARY SEALIFT COMMAND Mr. R. R. Askren - Member Lt. j.g. E. T. Powers, USNR - Member

vi

Mr. K. H. Koopman, Liaison Mr. C. Larson, Liaison

LIST

Where also

equations

provided.

are

reproduced

Each appendix

SYMBOLS

from

of their

symbols

are

list of symbols.

Definition

qh

Aggregate

B

Beam of each

b

Hull

horizonta

centerline

Block

I acceleration

hull spacing

coefficient

CLA Cw c

Waterplane Oblique

wave

c

Midship

coefficient

Do

Draft

d

dl-0.65Do

Centerplane

area

coefficient

coefficient coefficient

d]

Distance

of cross-structure

F Sc

Vertical

shear

Fsl

Maximum

shear

F so

Maximum

waveinduced

total

9

Gravitational

H

Wave

neutral

at iuncture

cross-structure

weight

above

base I ine and

hul I due

to

weight of cross%ructure

at iuncture

shear

I ess cross+

axis

of cross-structure

at iuncture

and

hu I I

of cross-structure

and

hul 1,

ructure

acceleration

height

RI/~

Significant

HL

Side

hydrostatic

force

on outboard

HR

Side

hydrostatic

force

inboard

h

Horizontal

L

Length

Ml

Maximum

wave

shift

between

and M=

definitions

references,

has its own

Symbol

Cb

OF

Moment

height

of center

shel I

shel I

of buoyancy

of one

hul I

perpendicular

vertical

bending

moment

at iuncture

of cross-structure

hull at iuncture

of

cross-structure

and

hul I due

to weight

of

cross-structure M.

Maximum

P

Maximum

s

Clear

wave-induced

bending

1ess cross-structure

hull

axia I force spacing

vii

moment

on cross-structure,

weight-

Definition

Symbol

T1 Tc

Maximum

torque

on cross-structure

abut

its twist

center,

t # o

To

Maximum

torque

on cross-structure

about

its twist

center,

t = o

t

Longitudinal

distance

between

axis

and

cross-structure

Centroid

of HR below neutralaxis of cr~ssstructure

width

neutral

LCG

of HL

Total

below

ship

Centroid

of cross-structure

of catamaran

Wave

surface

above

stil I waterline

at outboard

Wave

surface

below

still

at

Total

(both

g x added Wave

hulls)

waterline

displacement

mass in sway

of both

length

LCA Mass

density

Circular

wave

of water frequency

viii

—.

-.

hulls

inbcard

shell shell

twist

center

1.

INTRODUCTION

The history

of catamarans

it is only

in the

resulting

in the construction

Except

last decade

for one

pipe-laying

cargo

in Iengthl

except

(Russian). were

barges.

vessel

transverse

stabi I ity,and

research

good

However,

that

(Dutch)

for the

special advantage

I ity

these

ships,

to tuke

maneuverabi

all

to note

Duplus

that mainly

(2).

of serious

for use on the Volgar

the 400-foot

monohulls

a revival

in this

interest

century,

in catamarans

vessels.

it is pertinent

be recognized

over

(1) and

has been

oceanographic

Also,

for two,

It may

selected

references

there

of some sixteen

pose vessels , such as ferries, and

is old,

that

fishing these

and

boats,

large

under

purrigs

315

Kyor

feet

Ogly

catamarans

deck

offered

special

drilling

ships are

in question,

of the speeds

are

the 425-foot

purposes

at low

vessels

area,

by the

high

catamaran

configuration.

The question cial

sector

for low with

density

the

taken

has been

the

Navy.

pay

load .

Catamaran

Study

a comprehensive

Industries (6),

and

claim

and

for the

proiect tions

trade

obstacle

information

reported

here

of catamarans,

structural

knowledge

The features

the

catamarans?”

interest the

by General

of catamaran

prepared

- both

is related Maritime

technology

(2),

design

commervessels

Administration and

the

(3) and

catamaran

a preliminary

in the

to high-speed

Dynamicsr

of a semi-submerged

began

Navy (4).

Litton

container

of a catamaran

has under-

ship

(~) and

container

ship

(7).

in assessing

the desirability

to establish

the structural

was to investigate

into

appraise

existing

required

to insure

examined

that

the

design their

could

scant! ings , construction

cross structure

not large

this question,

performed

design

have

et al,

A SOI ient

To answer

assessment

Trans-Atlantic

of technical

“why groups,

(1)1

an actual

Fisher,

raised, In both

of large

structural

size

problems,

limits

and

has been

The purpose

technological

procedures,

impose

catamarans

requirements.

to size

determine

the

lack

of the and

propor-

the additional

adequacy.

limits

repair

were

powering

facilities,

and

and propulsion, harbor

and

pier

limitations.

In order at by

least

to estimate

the first

considerations

The maior design and

of the

comparison

Evaluation ture

other

effort

the

cross-structure

of the prel iminary than

of the

cross-structure. of al I available

of the analytical

analysis

Numbers

cycle

cross-structure

proiect

scantl design

scantl

was centered

methods

test data for estimate

methods.

in parentheses

refer

to references

I isted.

catamaran

to accomplish of a size

indicated

ings.

around

The task was divided model

ings it was necessary

of a large

into

on the

the procedure three

loads

parts,

on the

of cross-structure

for the viz:

structural

(a) Assembly

cross structure; load

and

(c)

(b) Struc-

2 New rnomentf tion

equat ions are proposed

axial

force

Modifications

and shear force .

of wave-induced

vertical

bending

are proposed

to an existing

equa-

for torsion. The project

scope was limited

semi-submersible

catamarans

made to analyze

the influence

Of all tion

and model

of catamaran

Appendix

1.

as well

of catamaran

Recommendations large

work

test measurements, aspects

or strut-stabilized)

of symmetrical

Considerable

important

catamarans .

as opposed

No attempt

hulls or non-symmetrical

hulls

to

was

on the size

of catamarans.

the aspects

in the past.

surface

to conventional

(column-stabilized

I imit or the cross-structure

2.

for the estimate

design,

resistance

has been done as their

resistance

has received

correlation.

as gathered

are made for the future

the most atten-

in the areas of theoretical A brief

from the I iterature

research

prediction

statement

on the most

is provided

in

program

for

and development

catamarans.

ANALYSIS

OF FEATURES

It appears, would

in principle,

preclude

that

the design that

wil I not be special

problems

development

necessary

dertaken force

effort

strongly

favor

without

The features a.

IMPOSE

the facilities

are no insoluble

exist

to build

to build or that

termincltioh

considered

considerations

catamaran is no need

vessel .

What

to design

some unknown

which

in the United

many ships immediately,

the venture

that

technical

there

an efficient

catamaran,

LIMITS

of a 1000-foot

to overcome,

a large

SIZE

that

for future

is meant and build

technological

States. there

research

is that

and

if eco-

one may be un-

problem

wou id

of the venture.

in reaching

the foregoing

conclusion

are as follows:

Resistance-Powering-Propulsion: Main

,, situation

and propulsion

in large

may require

limit

designed

machinery

not found

catamarans upper

there

a strong reservation

the premature

MAY

and construction

This does not imply

nomics

THAT

monohull

system for a large Depending

designs.

more than one propeller

to the catamaran

to accommodate

size,

assuming

per hull .

that

hull

catamaran

beam

However,

very

a

large

this need not set an

is sufficient,

Machinery

more than one propel Ier.

does not present

on speed and draft,

and form can be

weight

and volume

should

be acceptable. b.

Wave

Loads,

Cross-Structure

The hydrodynamic cwrse, Design

the differential checks

ing show that loads.

With

conservative thickness

unique

loading

for up to approximately cross-structure full

transverse

estimate

is 1-1/4

to be stee 1.

effect

wave

with

There

and

Structural

to catamarans

Material:

and of prime

on the hul Is to be absorbed 1000-foot

practical

bulkheads

of effective

inches.

$cantling

catamaran

IOO-foot

scantl ings can be designed

at approximately

flange,

with

consideration

the maximum

is no doubt

that

50-foot steel

is, of

by the !cross-ktructure. clear

to absorb

spacing

the wave

and making

(100,000 psi yield)

the cross-structure

hul ~

Platform

roll and bending

from the Livingston

test,

1,8

where

responses in a wide

it was found that heave

when shear,

Phase data

test results that

width.

heave

of regular

iti.

how-

steepness pos-

in beam seas are as follows:

maximum

ii.

whereas

tentative

maximum

cata-

moment,

one another.

in which

response

which

should

bending

maximum

and the hul Is due to side forces

force on the hulls cancel

sense genlarge

the hulls are at the nodes (with

experience

and hydrodynamic,

wave and ship locations

maximum

induce

inducing

to be of highest

When

they

of the cross-structure,

In the foregoing

would

is considered

two moments have opposite

suggestion;

the vertical

of opposite

when the crest is on the centerline

of the cross-structure

moment due to the weight

acceleration

force

condi-

is orI the crest and the

and at the same time

centerline),

both hydrostatic

the cross-structure.

vertical

If the wave

it is believed

for generating

When one hull

(damping)

ever,

si~e side forces,

have the potential

on the cross-structure

The velocity

crest or trough

1O-II,

on the hulls.

they experience

high shear force

maran roll .

Figure

approached

moment

Platform

range

zero

in

were maximum.

test in beam seas is as

follows: Maximum

shear 90°

out of phase with

Maximum

side force

in phase with

Maximum

yaw moment

90°

bending

bending

moment

moment

out of phase with

bending

moment Maximum

torsion

moment

180°

out of phase with

bending

moments are caused

bend-

ing moment This implies by vertical ing moment,

forces since

that maximum heave

and shear is 90°

is minimum

or zero

out of phase with

in waves

maximum

.-

which bending

by side forces and not cause maximum moment.

bend-

30 It on the ksis

can be stated that there is good agreement between the conclusions reached of the model test results and the visual inspection. This agreement pro-

vided

the encouragement

ment,

axial

to set up simple

force and shear force,

that the test data available

5.2

Development 5.2.1

to reach

of Design

equations

for maximum

whose presentation

follow.

the conclusions

is limited.

vertical Indeed,

bending

mo-

it is admitted

Load Equations

Equation

for Estimating

Moments

and Axial

Maximum

Force

Transverse

(See Figure

Vertical

11)

Assumptions: e Wave

is sinusoidal

s Wave

length

Wave

height

●

= twice >/1

=

hull o

centerline

space,

>

= 2b

(3.

Fig.

11

-

Loading

Condition

for

Maximum

Vertical

Bending

Moment

in

Beam Seas

31

●

Trough at centerline

●

Vertical

equals ●

of catamaran

acceleration

Magnitude

half

is lg (displacement

weight

and distribution

foot of length tion with causing

constant

magnitude

of the horizontal 1/4

draft

Cross-structure

weight

is evenly

●

Cross-structure

extends

between

t Velocity

per

sec-

acceleration

equals

the intact

wave

beam off the centerline

above

●

and the

as at transverse

side force

at a point

each hull and 0.65

force

beam

the dynamic

acceleration

of side hydrostatic

remain

maximum

c The aggregate

of one hull

of catamaran)

of

keel

distributed inboard

shel I of hul Is

ends are built in.

dependent

forces and impact

of wuter

particles

on the hulls are negligible.

Maximum

M.

M.

=

=

Vertical

Wave-induced

=

Moment:

bending

moment

for a weightless

over the breadth

of cross-structure

Side hydrostatic

force

center

‘MO

Bending

‘L

VL

=

=

- couple due to the horizontal + side inertia force moment

of buoyancy

(HLVL-HR

moment

VR)-+h+(A2:A

~gL

(DO+

2

d]-$

cross-structure,

YL)2

(D.

+ YL)

‘)ahd

=

=

. . . .. .. .

Side hydrostatic

Centroid

force

of HL below

constant

shift

(El)

on outkard

neutral

in

shell

axis of

cross-structure

Y~

=

}

cos(lT*)

= Wave surface above

still

waterline

at out-

board shel I

HR

VR=

=

qgL

dl-~(t)o

(D. -

. Y~)2 =

‘YR)

=

Side hydrostatic

Centroid structure

—

.-

force on inboard

of HR below

neutral

shel I

axis of cross-

32 YR

;C05(TT+)

=

=

Wave

c.

BE ---

=

h

2 (Do + YL) + (D.

23

(DO

-

+ YL) + (D.

YR)

- YR)

[

B

~

;3

Al

below still

waterline

at in-

1

flDo+yL ‘ -.—[1

=

h

surface

board shell

= Horizontal

.

Added

=

Aggregate

horizontal

acceleration

=

d] -0,65

Do = lever

cwm for inertia

=

Moment

mass of one hul 1 in horizontal

shift

in center

of buoyancy

direction

27 ah d Mc

at ends due to weight

Wc s

Ml

‘-

-n-

=

Maximum

=

Maximum

vertical

A&+MG

Side

=

P

bending

moment at iuncture

(E 2)

of

and hul I

*..

*’a. **n****

*

(E 3)

. . . . . . . . . ..

(E 4)

@*,.**.*,*.**

*..

Force

Maximum axial

=

P

of cross=structure

**,..,,.,.. ...................

cross-structure Ml

force

comp~e~ion

A+A1 — 2g

HL-HR+

ah

Due to the symmetry

of the assumed wave

t~ set down the equations

of moment and axial

and vessel ~ it is possiblel force

for the condition

by intuition

of wave

crest at

centerline. Ml

=

Ml

=

Ml

=

P

=

Maximum

vertical

bending

(HLvL

- HRVR)-

moment at the iuncture

of cross-structure

and hull

Wc s

I

Muximum

It is important for trough

axial

$

h + (~

tension=

“hd

I ‘T

A+A1

I

HL-HR_k~’

to note that absolute

at center! lne.

+ ~)

values

()

are signified

ah

since symbols refer

to figure

II

33

It should be recognized will

result

in the higher

Mc

and P.

However,

stress due to axial

that whether

direct

crest at centerline

stress wil I depend

by rough checks,

force

was greater

or trough at cepterl

on th~ relative

it was found that

ine

size of stress due to

for existing

catamarans

than stress due to cross-structure

weight

(or local

loads),

5.2.2

Equation

for EsFirnating

According shear occurs, this position

probably,

to the analysis

when one hull

the hulls experience

one another.

Again,

time as maximum

accordin~

force,

for maximum

shear coefficient

cal wave-induced

of vertical

=

0.41

=

Wave

equation

of this section,

acceleration

maximum

maximum

in the trough.

in opposite

]n

direction

shear.

his

Cw

w

induced

in the case

by picking

cross-structure only.

an im-

of vertical

bend-

the highest

sense,

6.

to obtain

Since the verti-

hen, (E 5)

weightless

Wc

*.*,,,,.*,

=

-T

FSc

=

Shear at ends due to cross-structure

F~l

=

Maximum

shear at iuncture

(E6)

........ ..

Fsd

weight

of cross-structure

and hull Fw

=

5,2.3

+ Fsc

●

Equation

for Estimating

Dinsenbacher’s in Appendix Tc

torsion

(E 7)

● ✎✎☛✎☛✎✎☛

Maximum moment

Torsion Moment

equation

which

is also reproduced

3 is =

=

Torque about Torque about shear acting

Tc

✎☛✎✎✎✌✎✌✎✎

=

I

$Cbg

center

of twist

center

of gravity

through

BO.6

~L2

of cross-structure of ship + torque

the ship’s center \2~

+

due to

of gravity 0.14

Mqt/S

an

nondimension-

the cross-structure

, . . . . . ..s. . ..**...,.

shear at ends,

not permit

test data

from Figure

on the hulls are of opposite

lg acceleration ~

and rol I will

to resort to the model

is done simply

for a weightless

+

acceleration

cross structure

Fsl

to

roll should occur at the same

as it WS possible

It is proposed

acceleration

can be assumed fo have Fso

vertical

to the analysis,

of a shear force

ing moment and axial al ized

at the beginning

shear,

writing

expression

Shear Force

is on the crest and the other

maximum

Combination mediate

Maximum

34

Torsion values with

the model

test results,

for the ASR model . term of secondary

as provided

by the first item,

as was done in Figure

Even for the ASR model,

in an irregular

T1 would

sea with

of Miami

nificant

wave

provide

50-foot

model

height

design purposes.

torsion

significant

It is pertinent

to point

of maximum that

is half

of maximum

would

be

If

t

=

shar

shear.

except

the second

to replace

$c~ I

the second

Even though

the use of

in light

shear in oblique

to a weightless

L2/~n

JXL2/2~

distance

maximum

seas is approximately cross-structure.)

to assume that shear in phase with

I- (t)

[1 +

(0.53

(t)

from ship LCG

the torsion

x0.5xmax

0.11

$

Cw

twist

center

= O

then =

T

To

=

5.2.4

Comments

s The equations neglect ticles ●

0.7~

$Cbg

are quasi-dynamic

velocity

dependent

and semi-empirical

forces as well

any other assumption

it passes the catamaran seen that wave

with

wave

would

hydrostatic

The new equations ciated

would

than

in nature.

as the impact

them.

presented

that wave

be difficult

form does deform

the deformed

forces or larger ●

Equations

of water

They par-

on the hulls.

Although

that

L2/2~1

on the Proposed

between

form remains

intac~ as

to handlel

in reality,

the hut Is.

it is conjectured

not cause higher

loadings

than a wave

acceleration which

do not have any lmck-up

torsion

equation

shear in beam seas)

+

to cross-structure

test

of the obiection

test results,

~

II

of the limited

the equation.

model

(This applies

be conservative

for

selected

term in light

to the

sig-

severe

Dinsenbacher

using the symbols of this report,

0.7

Longitudinal

that

due to the

A 50-foot

sufficiently

moments.

According

in T1 was re-

if the data scatter

is iustified

and maximum

O.6

as any test value

test is neglected.

Then,

$Cbg 0.7 =

height

of torsion

in beam seas.

it would

if the constant

out at this time

3 of this report.

shear and torsion are out of phase,

Tc

was zero

making

at least as large

that had to be made to derive

It is proposed to it in Section

It is conjectured

wave

torsion , conservativeness

data and the many simplifications

Tc

small

sea state 8 and it is considered

O.6 to suit the ASR long term prediction

53 percent

7 that

values

test and the undisclosed

represents

O.7 may overestimate

raised

can be compared

importance.

by O.7 then

University

T1,

t for model

t was relatively

It can be seen from Figure placed

7, since

it is

dependent

remains derivation

intact. asso-

35

The procedure

for calculating

used by Schade The use of ~ with

test results which

refinement

The method

the added were

there

to consider

independent

one another’s

hul Is is quite

opposite sense. Unfortunately, have sway results to evaluate

Figure

9,

of Loads Calcu Iated

posed equation

wave

7, 8 and 9 provide shear,

and torsion

and other

As a matter

5.4

by , Pro~osed !

for the catamarans moment

using Series 60 data,

method

The reason with

~x

could

being

that

2W and

Eauations

respectively,

listed

in Table

2,

as calculated

the vertical

by the pro-

Other methods include model tests, Scott’s method an d Lankford’s method for torsion moment due to

shear and bending

were also calculated

height

Method

remains

constant.

weightless

moment

for a wave The values

with

cross-structure

for the Thornton, ~

since

$SR,

= 2b and H = ~\~10

of maximum

load/wave

height

for Design Loads Estimate 10 presents

developed

and the oblique

and for

from the test reports.

Table equations

frequencies)

methods.

of interest,

Platform

load/wave

were obtained

do not on added

Method

grounding. Al I calculations are for catamarans with model tests results are for weightless cross-structure.

assuming

in waves

to be slim.

moment and torsion,

and Livingston

can constrain true

of the two hulls have

the proposed

moment.

of the critical

Com~arison and by Other

for bending

the bending

of occurrence is likely

Tables

since they

encounter

that for sma I I catamarans

H =2W/10

moment,

hul I as if they

be particularly

estimates

on

Whether

model test results gathered this. Until new information

hulls is forthcoming,

much overestimate

frequency

bending

information

wil I have to suffice.

It is suspected very

hulls and form of hulls.

acceleration

(wave

The

and simplicity.

for catamarans.

questionable

mass in sway at low frequencies unsymmetrical

symmetry

mass of each

This should

2b where the horizontal

with AS

to 2 .OW.

is no published

direction

the added

sway motion.

in accordance

1 .8W

for unsymmetrical

mass in the horizontal

it is satisfactory

~=

to sustain

As far as it can be determined,

is the same as

is not quite

suggest

is sacrificed

does not account

force

(12) and (13).

= 2b in beam sea condition

the model

possible

side hydrostatic

and Dinsenlmcher

a recommended

in Section

seas as given

5.2

design

load schedule

and the ratios of the maximum

in Table

which

is kased on the

load

in the beam seas

6.

.-

36 Table 7 - Wave-Induced Transverse Vertical Bending Moment in Beam Seas Nntm[ Al I ~uluw

E.W,

m nlnulo ampl Itudm In foot tom andfor walght Imncronl-ntructu; A5R

E,W, Thnrntm $hlb A

Thornton

ASR

M

(2)**Calc.1/1000Hl@h-it In SW S!at* 8

33.24o

1,045,244

32,547

3,091 ,9a2

(3) SR 192 M,thod

50.4sa

1,426,323

40,518

4,195,741

(4)

SA,4

I ,020,000

729,000

Lavlnnmtun PlatfOrm 199,206

4,325,545

51,925

Note: All values are single amplitudes in foot tons and for

220,764

756,000

1,947,,Brn

244,400

weightless 54,040

1/2

55,051 0,443

(6) (1)/(3) 0, (2)/(3)

0,459

(7I (~)/(4) or W(4)

0,440

1.255

(q (3)/(5)

0,933

0.734

TermPradlotlon of Maximum

0.421

0.737

cross-

structure

200,407

0.803

(9)*** lonu

** ***

Mohole Platform ——

(Scbttli Mmthod)

(5) ~(%o)

k

U, of Mldml Ship A

0.903 0,944

0,936

O,aob I ,100

63,300

Max. or I/1000 hlghc~t, wh Iahavm Ii grater RAO from model ban?nEnd ma ntate dadhd ~ Plwio~-Moikowltz From R*fOrOnce @)

5peatrum

Table 8 - Wave-Induced Shear in Beam Seas Nata: All valumI are tln~le ~mplltuda 1~ foot iom and for wrnlgk

E .W.

Thornton sh!p A

E.W. Thornton

ASR ASR —

w

(1)

Note: All values are single amplitude in foot tons and for weightless cross-structure

Im crom-~tructure

U ,oF Mlaml Ship A

Maholo Platform

Lovlng!ton Platform

6,450

2,4ao

1,190

(2)

**culc# 1/1000 Hl#hmt In Sea slate 8

551

6,9M

2.02

9,134

.

.

.

(3)

0.41 (A /2)&’W) (Cw) SR192 M*thOd

749

10,110

304

9,880

.

2,9&3

I ,40U

605

.

349

.

.

.

I ,0

0.923

.

0.837

(4)

~O(2b/10)1/2

(5)

(1)/(3)

0.726

or (2)/(3)

O.&b

—

*

MEX. or l/1000 hl~hmt. whlchovor It oraatar

Table 9 - Wave-Induced Torsion

Moment

in

Oblique

Seas

**** A5R

Therntcm Ew. (1) KModel Tait lvidx. [n S* State 8

Thornton

~

1,625,000

-

193,452

I,ao,ooo

1B,810

\ ,090,000

1,35,000

2,206,BB

23,495

2,433,077

2,526,971

2S,560

11,055,502

I ,043,no

1,044,577

(3) ***

41,400

4a,240

L@vln@ItOfi Platform 93,304

Note:

009,401

5a,545

(4)0.04LA

Moholo Platform .—

9,536

(2)** Cal,, l/1000 Hltih01! In s-a Stato 8 Sk 192 Mnth.d

J!!!&

M

U” OFMlqml Ship A

-

192,000

99,500

eo,mo

(Scott’i Molh.d) (5) 0.175 LA (Grbmdlna)

2~195B

9,455,092

102,790

10,444,711

350,350

(6) (1)/(3) or (2)/(3)

0.95

0.02

0.5!

0.74

I .2b

1.01

0.94

(n (1)/(4)0,(2)/(4)

0.86

0,47

0,44

0.33

0.64

0.81

1.16

* ** +** *w.

bx. or 1/1000 high.tt, whlahmvw II orutmr RAO from modal tmnraEnd UE Bmt. d#narlb*d b pl@rmn-Malk*wlt~ $Cb~Bx0,7~ L2/21Y A~,”~*d L = LBP. 5 H

sP=ttum

—

values are single amplitude in foot tons and for weightless cross-structure

All

090 0.850

37 Table 10 - Design Load Schedule

Loading for Direci Stressat Midspan of cross-Structurs Beam Waves

Load

Oblique Seus

Axial Force

P from (E4)

0.48 of P from (E4)

Moment, Weightless Cross-Structure

M.

O.&

LOCQILoad (CrossStructure Weight)

Wc

from (El)

of M. from (E 1)

Wc

Loading for Direct Stressat Juncture of Cross-Structure and Hul I Axial Force

P from (E4)

0,48 of P from (E4)

Moment, Weightless Cross-Structure

M. from (E 1)

0.48 of M. from (E 1)

Local Locsd(CrossStructuresweight)

WG

Wc

Torsion

0,49 of Tc from (Es)

Tc from (E8)

Loading for Shear at Juncture of Cross-Structure and Hul 1, Acting Concurrently with Moment Torsion

0,49 of TG from

Locol Load

Wc

Tc from (E8)

(E8)

Wc

Loading for Shear at Juncture of Cross-Structure and Hull, Acting Out of Phase with Moment Shear

0.53 of F~o from (E5)

Fso from (E 5)

Local Load

The method

schedule. to estimate obiects

and

is considered

It will

be noted

In the

opinion

that

depth.

~ested

that

individual

weight

and

real istic

AS

designer support

and

grounding

to vessel

speed,

docking

consider

oblique

appropriate

designs.

loads

are

not

torsion

loads

are

nearly

shape,

size

far as torsion loads due to docking

points

..

for conceptual

the grounding

of the authors,

as they are so subjective water

satisfactory

docking

with

to his vessel

.,.

included

and

strength

are

concerned

most likely

in the

impossible of striking it is sug-

docking

.

.. .

38 6.

HULL

FLEXIBILITY

It was apparent lishment

AND

at the beginning

of catamaran

preliminary critical

size limits

structural

loads were

Lankford’s available.

analysis

method,

a method

which

structural

calculations

discussed

in Section

at their

junction.

using Lankford’s

at once that only the hull were

simulated

method

bending

fluence

partially

of hull

rotation

it was deemed

weak-

between

the

desirable

to find

for which

Research

attraction Catamaran

were available

and it was decided for which

in-house.

and shear deformation model .

struc-

It must be menin the longi-

The space frame analysis

by its flexibility

is inherent

indicative

and the relative

numerical rotation

on the cross-structure, on the individual

hull

to values

between

and the in-

structure

in the

area .

The method proiect

is computerized

if structural

changes

It can include

which

analysis

[t can assume several

different

maximum

could

be a great

was necessary

in the structural

and secondary

mathematical ●

was readily

were available.

at least,

flexibility

of the cross-structure

transition

mary

2,

two maior

and to try it out on a vessel

flexibility

the hul 1s and the cross-structure

●

for the

once the

in Appendix

is no relative

in the mathematical

It should provide,

on the influence

quick

catamaran,

to have

had an immediate method

of structure

the method .

●

the estab-

method

advantages:

s Representation

●

of a large

Hence,

16 Oceanographic

based on Lankford’s

had the fol lowing

a suitable

it appeared

and there

of space frame analysis

direction

in order to attempt

3 and detailed

previously,

did not have these weaknesses

calculations

tudinal

that

to select

of the cross-structure

to try it out on the T-AGOR tioned

of the project

It assumes the hulls to be rigid

The method

STRESSES

it was necessary

as mentioned

hul Is and the cross-structure

tural

TRUCTURE

estimated.

However,

nesses.

CROSS-5

amount

asset later

for several

types of loading

in the

ships.

at once and permits

configuration. of structure

loads by employing

effective

progressively

in taking

pri-

more detailed

model .

[t can conveniently

handle

structure

with

more than one material,

say

steel and aluminum. Figure

12 shows the bare

ates its mathematical the IBM- 1130

“Stress”

model

outline

of the T-AGOR

incorporated

structure

and Figure

in the space frame analysis

which

13 delineemployed

program.

The analysis used the original T-AGOR 16 design loads. The loadings which control led the primary members of the cross-structure were the grounding loads and the transverse

vertical

suggested

by Lankford

necessary

modification

bending

moments in beam seas.

and the latter to reflect

were obtained

different

—

principal

The former were obtained

from the ASR load estimates characteristics).

as (with

39 /

/ (

L KT,

/

L

04

%

LENGTH

/

PE12!7 —

22:

/ Y“l A I 11 ~1 ~; 7Z

/

/

1 < S’z

t! 23

< 37

?7~o” 34’-O’d zl~d’ 19’-6”

— HULL CLEAR5PACING — DEPTHTOMNW, AT51DE WiTH OFCR055STF?(KT, AT~ — —

o“

,$. o~~

BEAMoVEEALL — BEAMEA HULL — HULLh 5PACING—

/

24’- o“

51’-d

Fig. 12 - T-AGOR16 Structural Configuration

5---

-NEUWU

2

NOTE HULL AT

LOA!25 JOINTS

AXIS

OF

Fig.

The resulting condition Table

THE

THE

Other

13 -

Structural “Stress”

Model Program

less critical

conditions

and grounding

are provided

in

Design are also tabulated

than the cross-structure

for comparison.

are not tabulated,

Imsed on American

since

the

Bureau Rule and their

stresses

readily. the following

and cross-structure The flexural

conclusions

with

those taken

using Lankford’s

Those for beam condition stresses are less critical

.—

with

respect

Imsed on the structural from the T-AGOR

model

are in

16 structural

method.

. The shear stresses for grounding

the discrepancy

can be drawn

stresses:

stresses calculated

good agreement

.—. —

output

are omitted.

16 Structural

other

From the tabulation,

analysis

For IBM- 1130

The flexural stresses and shear members based on the stress program output and those

in the T-AGOR

can not be calculated

●

T-AGOR16

from the “Stress” program

design for those members were

flexibility

of

moments and shear forces in the beam sea condition

Stresses in the structures structural

AEEmtiTNUMBEFC3.

HULL%

stresses in the six cross-structure as calculated

HULL

NWTKAL

for the cross-structure

11.

OF THE

LWCIECLM?%UEE5

INTRODUCED ALONG

MI>

: Cli?CLED FIGuEEE.AE’E ME14Mt2 NUMM%5,

conditian

show less a g rep than flexural

are in fair agreement. m e n t.

Since

the shear

stresses in beam sea condition,

in shear stresses is not considered

important.

to hull

40

a It appears, duction

admittedly

bed

on this limited

of the longitudinal

flexibility

on the stress in cross-structure, the hulls @ Since

to be rigid

simplified,

structure have

method,

cross-structure

such as Lank ford’s

transverse

modulus,

requirement

addition

~nd torsional

and component

method,

to hull

about

frame

longitudinal

(decks,

assumes

model

can be theyall etc.

the preliminary

with

Detail

analysis

a conventional

the same accuracy

analysis.

cross-

i e,,

shear area,

that

handled

in results,

design

such structure

cross-structure

bulkheads,

which

similar,

of inertia~

flexibility

the introinfluence

al I the transverse

it may be stated

with

deformation,

structure

study,

can be conveniently

as the space

that

selection.

the mathematical

moment

of the last two conclusions,

the same time ccmsider,in

rigid

can be assumed structurally

the same section

of a cat~maran

the scantlings

For a prel iminury

bulkheads

onlyr

has small

i .e. ~ the simplification

not affect

the hul Is can be assumed

greatly

In light

would

check

of the hulls

deformation

and about

analysis

response in various

should

as the hull directions

etc. ) deformation,

Table 11 - T-AGOR16 Catamaran Stress Summary Section Modulus

Bhd —

Shear Area

ln2

[n2 ~~

Mmmber

Bend. Mom.

—.

KiJ&

m Beam

6&7 15&16 24 &25 32 &33 41 &42 50 &51

96 84 72 52 z

105.0 102,0 82.5 94.9 102,0 120.0

650.0 833.3 632,9 784.6 633,0 B53.0

Secl Condlfion

16,900 19,244 19,749 24,951 21,901 20,471

74 67 M 55 74 70

Grounding

7.

DESIGN 7.1

105.0 102,0 82.5 94.9 102,0 120.0

650.0 833.3 632.9 784.6 833”0 853.0

647 15 & 16 24 &25 32 & 33 41 &42 50 &51

94 84 72 52 37 23

that

U .S.

[oined

crfloat,

together upper

limit

were

loads predictio~

was to make a preliminary that

structural

that

Whether

was dependent

the cross-structure

that

shipbuilding

on the premise

able

23.6 23.9 24,1 26.5 23.9 26,5

3.3 3.1 2,8 2.8 3.1 3.2

21.0 11.0 6.6

9.1 5,0 1,4 0.3 5.4 9,3

21,4 11,5 8.1 4.2 10,B 8.9

10.5 7.7 4.6 3.6 7,6 10.8

limits,

Section2,

Condlflon

952 506 116 24 554 1,114

13(619 9,216 4,187 2,535 10,999 15,780

of the features

existing

foot catamarans

believed

0.7 0.7 0.0 0,5 0.7 0,7

1$; 18,5

SHIP

The analysis

structure

24.6 23.1 31.2 31,8 26.3 24.0

Purpose

indicated

able

Strew, Klps/ln2 $Wesn Program Design Calca Shear Flexur91 Shear Flexural —— ——

Shear

individual

1000-foot .

Hence,

and structural design

design

information

hul Is would should

the necessary once

analysis

were

would

become

scantling

1000-

in a drydock

be proposed

and

as a present

prob-

size and the weight

methods

1000-foot

apparent.

approximately

be built

evaluated,

the inadequacies,

size

handle

the available

of an approximately

in the course of the design,

catamaran

could

length

on whether

practical

may impose facilities

the logical catamaran.

if there

of

for cross-

be any,

next step Also,

it is

of the avail-

41

Table 12 - Design Ship Particulars

Hull

Symmetry

Length

Bet.

Perp.,

Beam Overall, Beam Each

Symmetrical 9421- oil

L

W

Hull,

B b (corresponding

Hull

~Space,

Clear

Hull

Depth

to Upper

Depth

of Cross-Structure

Length

Spacing,

to ~ b – -0.21)

S

Deck

at Side

of Cross-Structure

Draft Cross-Structure

Clearance

from Waterline

Block

Coefficient,

Cb

Coefficient,

Prismatic

Speed

0.572 0.701

Cw

(corresponding

Horsepower

to —v FL

-– 0.24)

52, L87 Tons

Weight 28,439

Cross-Structure

5,598

Electric

1,150

Plant

2r&o 280 5,950 3,800 4,790

Propulsion Communication Outfit

& Controls

Systems & Furnishings

Margin,

25 Knots 150,000

Hu I I Structure

Auxiliary

Tons

0.952

Cp

Coefficient,

Instal I Shaft Lightship

-011

0.54 CR

Coefficient,

Waterplane Service

301

90,800

Displacement

Midship

300’- o“ 100’- o“ 200’- o“ 100’- o“ 106’- O“ 45 ‘ -0,, 8oo1- oli 31’ - o“

10%

38,113

Deadweight

Tons

Container

Capacity

@ 11 Tons/Container

3, 10 I Containers

Container

Capacity

@ 15 Tons/Container

2,247

Containers

Container

Capacity

on Upper

3,136

Containers

Deck,

8’ x 8’ x 20’

I

LBP

WIDTH F 30~

= 942’-0’

D!5AFT =

31’-0”

I?EPTH

~T

DISPLACEMENT

= 90,800

= 10~-

I

0“

ToN5

Fig. 14 - Design Ship Profile and Plan

‘o“

200 100’-

o“

I

100’-0’

100 - a“

I

I

I

1

I AVEt?AGE

HULL

I BHD

sHIP

F&6 s .62%”

4

SYMBOL (HIT,)=

FOE

3TEEL1

MINIMuM 100 000FSl 5TRE NGTH E%EEL

ylELD

(B, H,) = AM GRADE B.H. SKEL = MILD STEEL

(M.5.)

Fig.

15

-

Design

Ship

-

Typical

Bulkhead

Structure

43 7.2

Design

Description

The preliminary The readers suitability

can expect to provide

bulkhead

design presented

improvement.

that

if large

the limited

It is assumed that payload

catamarans

carriers

.

ous plating

the vessel would

12 lists the design

terline

spacing

etc.,

particulars

can all absorb consider-

ship since

to monohulls

it is well

it would

and Figure

made to obtain

that the design’s

to ship length

To design

for Froude

a 36-knot

speed would

which

by far.

accepted

be as high-speed,

14 shows the profile

hydrostatic

properties

and vari-

areas.

and O.3 respectively,

spacing

system,

be a container

found superior

A rough set of lines were

It wil I be observed 0.4

assumed framing

are at all

Table

and plan views.

(or recycled)

from the authors for the design other than for its The selected shape coefficient, information desired.

and deck arrangements,

able

here is not optimized

no more defense

ratio

of 0.21

suggested

was considered

render ratio

would

the design

of 0.3

impractical

require

require

and the hull

to the values

characteristics .

hull

To design

centerline

cen-

of 0.3

to

(see Appendix

1).

It was felt

that

a speed of 36 knots.

uneconomical

would

number of 0.24

do not correspond

for good resistance

number of 0.35

to ship length

Froude

for hul I centerline

spacing

of 314 feet

.

The 100’ x 800’ cross-structure

is composed

of four structural

decks,

includ-

ing the upper deck

and the bottoml and seventeen identical full structural transverse bulk The cross-structure is assumed to be fixed at the inboard shel I heads spoced at 50 feet. of the hulls. full

In order to validate

transverse

structure.

bulkheads

Figure

15 depicts

Figure

16 provides

the catamaran

American

section

moduli

7.3

bending.

above

tional

following vertical

of the assumed effective

section

modulus

for the hulls

structures, bsed

on

the

It will be noted that the minimum permissible modulus considerably in excess of that required. This is

depth as compared

to a monohul 1 to have sufficient

for Effective

Structure

Explanation

is warranted

for the structure

On the face of it an immediate the deck plating strength

The structural Lankford’s

method,

Appendix

axial

by the bulkheads

together

with

The effective

, rather

(as distinct

moment,

assumed effective

question

be considered

calculation

analysis

bending

the two hulls.

modul i of the individual

cross-structure

the waterline.

longitudinal

head.

sketches

of the

of the cross-

at a bulkhead.

on the section

Explanation

why should all

decks and bulkheads

rules.

in a section

due to the increased

It includes

and the required

Bureau of Shipping

scant lings result clearance

.

four of the decks and seventeen with

structure

the information

hulls and the cross-structure calculated

this assumption,

in the hulls are aligned

effective than

iust 24-foot

In Lankford’s

force , shear as well effective

deck

in bending

from the design 2.

plating

deck

plating

breadth

in cross-structure

may come to the mind of the reader; iust as in the conven-

breadth

load estimate) method,

as the torsion acting

all

with

each

bulk-

was performed

the principle

moment,

as fixed-end

of 24 feet was calculated

loads,

are absorbed beams between by reference

44

I

--AK+=%= Y-J--+’* Main

;

Section

Modulus

=198,500

ln2

,,,:,

Section

Hul I

Required

by ABS

Ft per Hull

Modulus,

Including

10% for

Longitudinal:

~“;

I

0.50” ——— —,.

–k””-” ‘-- ““——

Main

T7----~

Dk

0.75”

Deck:

269,000

ln2 Ft

Bottom:

266,090

In2 Ft

Hulls

F::ETe ‘“k“‘H”’”)

P

~12’’x6-l/2’’x27#

al

/ Q_-

-1 -“”f~y

0.625”

l/T

(H.’.

Cross. Structure Effective

)

Bhd PI (H. T.)

5/8 “ X 24’

(BH)

~*v-

ln2

Axial Load Area [n2

j! . _,~ -, 0.50” Bhd PI ..! (MS)

1-1/4” x 10’

148,800

Modulus

Shear Area, ~--,...

Piating

Four Decks

Section ,n3

I

““

130,056

300

300

923

803

●

L

s.

0

J---AL

‘BH)

1

0.625”

Bhd PI (H.’.j

Symbol

for S*eel:

(H. T.)

= Minimum Strength

(H. T.)

(B. H.)

= ABS Grade

(M. S.)

=Mild

Cross-Structure

Fig.

16 -

Design

Ship

100,000

Section

Modul i

psi yield

Steel

Steel

B.H . Meel

45 to the wel l-known considered 50 feet

paper

as multiple

between

(24) on }he subject

webs for each deck

webs.

Among

ered by Professor Schade, j

by Professor $chade. with

the various

load and fixed

[mding

at

the smal I er effective discussion

moment

breadth.

and with

side shell

as double

The 20-inch 16,

was reached

this is provided

that

web plating

Appendix

the same section

10 feet should

plating

is 97°10.

of the center webs.

(see

bulkhead

web,

Figure

The reasoning

for

2.

inch plate

a 10-foot

thickness

modulus as available

be quite

of the deck

of the outer

16 also shows that if arbitrarily 1-1/4

maior

was used as it gave

no centerline

at top and Imttom

of the length

- equal

Professor Adams proved

breadth

of

consid-

viz:

the structure’s

combination

for a monohul I with

the effective

one-sixth

effective,

proximately plate;

webs,

by Lankford,

Figure be considered

Even though

bothends, the latter

paper)

effective

by taking

ends.

in question,

were

width

of load and end fixity

to the structure

Using the same reference,

to Professor Schade’s

The bulkheads

of 100 feet and plating

combinations

two were appl icable

moment at both ends or uniform is due to equal

length

deck

would with

plating

be necessary

5\8-inch

width

were

to provide

x 24-foot

to ap-

effective

conservative.

interpretation

Although 24-foot effective breadth was arrived at with prolmbly adequate that the structure in question is real I y of the structural i t is acknowledged

integrated

box structures.

to derive

effective

7.4

Further,

structure

Cross-structure

in Section

Thornton

and ASR Series,

is insufficient

in i ieu of the method

test data on box girders employed.

Loads and Stresses

The wave-induced proposed

that there

directly

design

5 of this report, Section

14 were

4,

summarized

in Table

equations.

The stresses are within

loads as deduced

from the method

by Dinsenbacher’s are summarized

calculated

(13) method in Table

by using maximum

the allowable

13.

(labeled

SR-192)

and from the The stresses which

loadings

predicted

stresses for 100,000

are

by SR-192

psi yield

strength

steel .

calculated

Although grounding is not considered a design criteria, for the grounding condition and are included in Table

to be considered

as a design

as the shear stress is 47,280 7.5

Design a.

criteria

the selected

inadequate

Conclusions

Direct

stresses are higher

Required

largest

The required

largest

related

100,000

psi,

seas than

thickness

to value

scantling

on a hopeful Iy conservative true only

in beam seas than

in oblique

deck plating

on the assumptions

.. .

be quite

lb/in2.

Shear stress is higher

b.

scantl ing would

stresses were also 14. If grounding was

is very

of effective

of approximately assumption

structural

seas.

much dependent plating. 1-1/4

and steel yield

are common to shipbuilding

for the particular

in oblique

in beam seas.

today.

configuration

inch,

based

strength

Of course, employed.

of

this

is

46

c.

If grounding structure

d.

wws to be considered

would

be quite

The imperative (17 bulkheads

a design

criteria

need to sustain and four decks)

the continuity

of structural

of the cross-structure

hulls causes the main hul Is structural

configuration

cal,

monohull

e .g. , unlikely

foot main

that a 1000-foot

bulkhead

the assumed

inadequate. members

into the main to be uneconomi-

would

require

50-

spacing.

Table 13 - Design Ship, Wave-Induced Cross-Structure Loads BEAM SEAS: MAXIMUM

TRANSVERSE VERTICAL BENDING

Single

Amplitude

MOMENTS

in Foot Tons Method

Weightless

1,658,464

:,061,106

Cross-Structure,

71-- .... L-.. r— —!-. Inornron ~erlea

Dinsenbacher

SR-192

2,048,785

At?nHJR

. >eHes

2,869,346

Constant with

Cross-Structure

?,427,439

Weight,

3,966,364

At ends of Cross-Structure BEAM

SEAS:

MAXIMUM SHEAR AT ENDS

Single weightless With

Amplitude

Weight

BEAM SEAS:

5,636

30,646

36,411

MAXIMUM

Single

in Tons

8,M6

Cross-Structure

Cross-Structure

At Midspan

Amplitude

AXIAL

SEAS:

MAXIMUM

Sinale

Amplitude

8,032

FORCE

in Tons

* 52,367

OBLIQUE

5,9ia

33,074

TORSION

MOMENTS

in FOO~ Tons

*** >,948,449

* Used for Structural Analysis ** Assumed Cross-structure Weight ***

Assumed LCG

= Steel

+ Ship’s

with

Longitudinal

of Ship Coincides

Cross-Structure

Twist Center

2,403,794

2,527,242

Deadweight Location

of

2,188,600

47

8.

TOPICS FOR FUTURE Researchers

have generally and the topics conclusion

(4),

(8) and (13),

very similar

for the desirable model

conservative b

(2),

reached

of this proiect

bY conducting would

(1),

RESEARCH AND DEVELOPMENT

unduly

.

However,

heavy.

Table

using existing

Also,

catamaran

Section

would

Modulus

Loading

Ins

=

300

ln2

Axial

=

923

ln2

BEAM SEA CONDITION Total

method

Shear Area Load Area

can be designed

Stress

148,800

=

(Trough

A significant

and generally

now

adopting

the resulting

be unacceptable

Cross-Structure

technology

in the technology

program.

structure

information

of the design

such an approach

Design Ship,

14 -

and development

design

.by nature

catumaran

as to the deficiencies

research

is that a safe large

tests,

approach

who h~ve appraised

conclusions

future

PROGRAM

a

structure

if a large

num-

Summary

(See Figure

16)

at Centerline)

on Cross Structure:

Vertical

Bending

Torsion Moment

Moment = 0.53

Without

x Max.

Local

Load (Cross-Structure

Axial

L~d

Cross-Structure

in Oblique

Weight

Seas

3,061,106 1,562,000

Weight)

Ft Tons Tons

43,960

Tons

52,367

Tons

32,527 5,535

Lb/ln2 Lb/]n2

Stress on End Bulkheads: Primary

Bending

Bending

due to Shear due to Torsion

Bending

due to Local

Load

-

34,169

Subtotal Axial

Compression

7,473

Tota I Stress Shear Acting

41,642 Concurrently

with

Bending

and

Shear due to Torsion Shear due to Local Total

Load

Shear

Out of Phase with

Bending and

Lb/]n2 Lb/ln2

Lb/ln2

1,371

Kips

2,897

Kips

4,268

Kips Lb/ln2

Torsion

Shear Shear Stress

—.

Lb/ln2

Torsion:

14,230

Shear Stress Shear

3,893

-.

4,039

K ips

13,463

Lb/ln2

.—

48

Table

14 -

Design

Ship,

Cross-Structure

OBLIQUE

Total

Loading

Stress

Summary,

(Cent’d)

SEA CONDITION

on Cross-Structure:

Vertical 0.48

Bending

Moment

xMax.

in Beam Seas

Without

Cross-Structure

Weight

1,469,331 2,948,449

Torsion Moment Local

Load (Cross-Structure

Axial

Load,

0.48

x Max.

Weight) in Beam Seas

Ft Tons Ft Tons

43,960

Tons

25,136

Tons

Stress on End Bulkh~ds: Primary

Bending

Bending Bending

due to Shear due to Torsion due to Local

Loads Subtota I

Axial

Tension

Total

-

Lb/ln2 Lb/ln2

3,893

Lb/In*

29,936

Lb/ln~

2,587 26,349

Stress

Shear Acting

15,613 10,430

Concurrently

with

Lb/InZ Lb/#

Bending and Torsion:

Shear due to Torsion

2,587

Kips

Shear due to Local

2,897

Kips

5,484

Kips

18,280

Kips

Total

Load

Shear

Shear Stress

GROUNDING For Reference Tots I 1.oading

Only

- Not

Used as a Design

Criteria

on Cross Structure: 12,850,000

Torsion Moment Local

CONDITIONS

Load

Ft Tons

43,970

Tons

45,500

Lb/ln2

3,893

Lb/ln2

49,393

Lb/ln2

11,288

Kips

2,897

Kips

14,185

Kips

47,280

Lb/ln2

Stress on End Bulkheads: Bending due to Shear due to Torsion Bending due to Local Total

Load

Stress

Shear due to Torsion Shear due to Local Total

Shear

Shear Stress

Load

49 ber of vessels were

contemplated.

sive list of study topics ensure the availability which

would a.

[n view

is prepared systematic

tend towards

The nature,

design

information

location

magnitude,

centerbody;

a following

to develop

comprehentechnology,

catamaran

and

structure

the optimum.

on the hul Is; the distribution terbody

of this conclusion,

to close the major gaps in catamaran

magnitude

and frequency

and location

and the hul Is.

of hydrodynamic

of loads in ~he cross-structure of local

These wi 1I require

wave

impacts

theoretical

loads

or the on the cen -

and experimental

programs. Model m

Test Program:

Series tests which etrical

hull

vertical

location;

cating

Series suitable

●

Model

b.

c. d.

e.

9.

extent

measurement

gathered.

)

structure

is relatively

It would

technique

be prudent simple

program.

Hull

for minimum

to clean

in various

unsymmetrical,

Added

mass and mass moment of inertia and unsymmetrical

bodies at wave

vidually

and as catamarans)

.

Construction

Cofitribution

to minimize

by cross-structure

modes.

and ship motions for multi-screw

encounter

in a seainstallation

motion

of sym-

frequencies

(indi-

bodies.

and compartmentation

Drydocking

is

mass and mass moment of inertia

of unsymmetrical

techniques

the data

whose cross-

for the horizontal

metrical

Added

once

to develop

analysis.

vibratory

resistance

Hull

stability

at

(Necessary

a catamaran

and amenable

particularly

feet.

and data analysis

way.

motion

lo-

the centerbody,

to select

response

form and spacing

in

distribution.

Dynarni cs of structural

Damaged

and unsymmvariations

and longitudinal

can simulate

load measurement

yard responsibilities). h.

which

and weight

FIJI I sca [e centerbody

the vertical f.

spacing;

.

test methods

form,

symmetrical

of hull

for ships from 100 feet to 1000

its weight

acceptable

include

longitudinal

of centerbody

~

least

would

forms; range

requirements.

need for new facilities

(ship-

facilities.

to the longitudinal

strength

of the

vessel . i.

Behavior

of Imx girders

under combined

bending,

torsion

and shear

loads.

i.

Stress concentrate ion at the hul I and cross-structure and extent

of necessary

reinforcement

and structural

juncture. detai Is.

Nature

for

.

50 9.

CONCLUSIONS

1.

The maior

constraints

individual

shipyard

to catamaran construction

size wit I be imposed

capabilities,

ckydock

by economics, facilities

and pier

facilities. Existing

United

proxinmtely be joined bors.

with

New

2,

facilities

hulls afloat;

drydocking

be essential problem

States yard

.

35-foot

facilities

Discharge

can handle

loads on large

draft

of cargo

information to provide

hull

spacing

model

great

in the streams could

tests to date

Additional

test data

optimum

have

research catamaran

an appreciable

ability

of unpublished

special

acknowledgement

their Friede

permission

plied

with

is feasible.

100-foot

beam

This does not

the model

through

test data

for specific

work

the accomplishment belonging

model

designs only and have

including

systematic

of reliable

design

of the proiect

to private

model

test

methods

for

THORNTON,

a copy of his senior thesis which

drilling

platform

was appreciated.

Friede

test data on their

Thanks are due to the Livingston for their

In this respectl

Dril I ing Company

test data orI the E .W.

to use the model

is due to the avail-

companies.

& Bates Offshore

whom the tests were contracted.

for permission .

developed

the centerbody.

for the establishment

is due to the Reading

of Miami

loads are not

structure.

degree,

lnc.

cross-structure

methods are not adequately

been performed

and development

to use the complete

and Goldman

providing

the pier

in either.

model test data

are also to be thanked for the University

harwill

of loads on the cross-structure prel iminary prediction of

draft

for predicting

analytical

of not simulating

programs are necessary

To

facilities

remove

long catamaran

and 31 -foot

confidence

had the drawback 5.

or new pier

for the estimation guidance to make

and the existing

to provide Model

have to

thafthe structural configuration willnecessarily be attractive.

sufficient

4.

would

in most maior

catamarans.

100-foot

The ava i Iable

3.

is acceptable

and modified

With respectto scantl ings, a 1000-foot imply

hul Is of ap-

.

Existing design is iust adequate

hulls,

individual

The hulls and the centerbody

1050 ft x 140 ft.

design.

Mr.

and Goldman

catamaran

Shipbuilding

for

and to lnc.

design

Company

John L. Glaeser

for sup-

51

The authors Ship

Design

wish

to thank

Division,

M.

Kaiii

Kyokai,

Messrs.

Rosenblatt

Sam T.

& Son,

Tsui and

N . K . K .

w ho assisted

Inc .,

with

Raman

of the

several

Basic

tasks of the

proiect.

Nippon ten descriptions

of their

Germanischer

general

approach

Lloyd

and

Det

to catamaran

Norske

design

Veritas

review

provided

which

were

writappre-

ciated.

Mr. cussions

Walter

Structure” Journal,

by Beniamin

Group

from

477-489,

for which

Jr.,

contributed

the authors Design

published

of The

grateful

1967,

Society

1970

Society

informal

.

Naval

of Naval

Loads

in October

by permission

with

of the ASR Catamaran

for Estimating

published

are

in August

of the American

“A Method

L . Dinsenbacher

pages

Eda willingly

“ The Structural

Lankford,

from

Haruzo

CrossEngineers

Engineers.

on Catamaran Marine

of Naval

Cross

Technology, Architects

and

Engineers.

Last, and

4,

Dr.

by permission

3 is quoted

by Alfred No.

W.

625-635,

Appendix Structure”

and

of the proiect

2 is quoted

pages

Vol . 7,

Michel

of some aspects

Appendix

Marine

H.

but not least,

11, Ship

practical

Structural

guidance

acknowledgements Design,

to the

Ship

proiect.

are

Research

due

to al I the

Committee

who

members provided

of the Advisory enthusiastic

dis-

52

REFERENCES

1.

General

Dynamics

Department 30 April

Bond,

John R.,

Eckhart,

M.

Jr.,

Leopold,

70

“A New

9.

15,

1970

Fisher,

Peter

A.;

Praught,

Lankford,

Beniamin ” American Naresh

in Irregular

10.

Scott,

11.

Robert,

of Naval

Michael

W.;

” Society 18,

- Dream

or Real ity, ”

“Structural

Center,

n167,

Analysis July

of

1970

Volume-Limited and Marine

Engineers,

Jr.,

“The Structural of Naval

“Motions ” Davidson

Catamaran Evaluation

Laboratory

Structure:

“Feasibility

Launch

and Marine

Design

ContainerEngineers,

of i-he ASR Catamaran

Journal,

Loading

August

January

and Hu I I Weight,

John

Report 2378,

Transactions, N.;

May

Pincus,

1965.

Appendix 70,

S.;

1962

“Model

” Naval

4 to

Society

Test

Ship Research

1967

Study for Ocean-Going Company,

Daniel

Catamaran

Mandel,

Volume

Cross Structure,

Cross-

1967

of a 106-Foot

Ship Types, ” by Philip

Engineers

Andrews,

and Tugboat

News,

“A Catamaran

Architects

Report LR-8231

Strength

of Novel

Alfred

Center

and Engineering

James E.;

Engineers

and Structural

and Marine L.;

Reporter

1969

of Sea Loads on Catamaran

H .A.,

of Naval

1970

Architects

$oden,

Dinsenlmcher,

Schade,

MA-4318,

Number

Society

Entitled

of Naval

Determination

the Crowley

August

Hul I Form for High-Speed

Society

Architects

and Development 120

Catamarans

Development

Maritime

April

W.,

M.,

Waves,

“A Comparative of Naval

No.

Publications

“ American

for Lecture

and

Ship,

Trade,

Meeting,

Structure, Maniar,

fm- U.S.

Contract

1969

lndus tries Twin-Hu[l

Section

Paper, Journal,

Notes

Ships, ” Society

ship for Trans-Atlantic

8.

on ASNE

Ship Research

Reuven A.,

January

Gulf

Service

or Reality,

Engineers

Outline

O.,

” Naval

Spring Meeting, Litton

- Dream

“Comment

Displacement-Type

6.

Information

under

1970

of Naval

Geoffrey

Catamarans, 5.

June

Society

Thomas,

Technical

“Catamarans

Journal,

American 4.

Study ’’prepared

Administration

to PB 183793.

Engineers 30

“Catamaran

Division), Maritime

National

1969.

PB 183787 2.

(Quincy

of Commerce,

California,

Catamaran, June

” Prepared

1965

for

53

i3.

14.

Dinsenkcher,

Alfred

” Marine

Technology,

Glaeser,

John L.,

“A Theoretical

and the Shear and Webb 15.

Institute

Livingston, E -W.

16.

Section

Meeting,

Michel,

Walter

18.

and Michel,

Naresh

oratory

Letter

Meier,

Herbert

19.

Chey,

Young

Loading

M.,

20.

Numata Davidson

21.

E.,

Walter

“Model

“Model

H.,

Alan

Senior

Thesisr

“The Catamaran

Architects

Drill

and Marine

Ship -

Engineers,

Gulf

Ship,

Its Features

and Marine

and

Engineers,

Its

Gulf

Sec-

Dril]ing

Ship, ” Davidson

Lab-

1965

Design

Volume

5,

of a Catamaran

Submarine

No.

1968

Tests to Evaluate

1, January Seakeeping

ic Vessel,

Rescue Ship

Qua] ities and Structural

” Davidson

La boratow

Letter

1962

Laboratory

of Naval

H .,

Test of a Catamaran

ocemograph

“1/100-Scale

Society

of a Catamaran

1968

Architects

January

Technology,

McClure,

Cross-

1970

Into the Motions

Catamaran

of Naval

“Preliminary

A.,

April

on Catamaran

October

1966

1052,

of a Catamaran

Report 891,

Lwds

4,

1961

Report

(ASR), ” Marine

May

“ The Sea-Going

April

No.

on its Cross- Structure,”

of Naval

February H.,

7,

Investigation

Moments

” The Society

tion Meeting,

for Estimating

Volume

Architecture,

” The Society

Thornton,

Maniar,

Bending

of Naval

C.W.

Feasibility,

17.

“A Method

L.,

Structure,

C.,

Model

Letter

Report

“Development

Architects

Tests of Mohole 1084,

January

of the Proiect

and Marine

Drilling

Platform

in Waves,

”

1967 Mohole

Engineers,

Drilling

” Transactions

Platform, Volume

” 73,

1965. 22.

Numata Davidson

23.

24.

Edaf

E.,

“Model

Laboratory

Haruzo

Water,

sactions

Volume

Schade,

H .A.,

73r

Semi-Submersible

Drilling

Vessel,

”

Report 1234

Jr.;

” The Society

C.

Lincoln,

of Naval

“Steering

Architects

Characteristics and Marine

of Ships

Engineers,

Tran-

1965

“The Effective

Loads, ” The Society 59,

Letter

and Crane,

in Calm

Volume

Test of a 6-Column

of Naval

Breadth of Stiffened Architects

and Marine

Plating

Under

Engineers,

Bending Transactions,

1951

—

-.

54

APPENDIX CATAMARAN

Of al 1 the tion.

aspects of catamaran

Considerable

and model

of this appendix

design,

represent

as well

valuable

certain

conditions,

tal resistance

published

to general

Contributions making

to resistance

Frictional tance

by other

and,

Catamaran (V/~L),

hull

theoretical reduce

calm water

wave

is general can occur

irrespective

as a ratio

not be compatible

where

given

between the level

From a practical constrain

the influence

surface,

of wave-

in this discussion. degree

agreement

speed.

is a function

of surface

rough-

resis-

number

the hulls can interfere

favorably

to

to the two hulls running

components

of the combined

wave

180°.

between Beneficial of

of the Froude

1 and 2) has demonstrated

appropriate

frequency

theory

in the Froude number

with with

effects

can be sepa-

or viscous and wave-making.

to the sum of the frictional

resistance

effects

drag to below

and model test data that

range of approximately hull

appears course,

separation

0.3