Draft Surveys

8/11/2019 Draft Surveys

1/109

CONTENTS

Introduction

-

Ship

Draft,

TYjm

and

StabiJ-itY

l{otes

Page

ChaPter

1

2

3

4

5

6

7

Draft

SurveY.

Cargo

Deadweight----

Trjm

and

StabilitY

Grajn

loading-

Rolling

Period

Test

for

G'1"

"

Appendi.x.

Draft

and

Stability

hoblsrs

arrd

Ansroers'

METRIC

INSTRUCTIONAL

MANUAL

for

"SHIPS

DRAFT

SURVEYS-

1

L4

30

50

5B

73

BB

94

94

I

((

0'

6)

t"

aptain

Gordon

G'

Glover


2/109

CHAPTER

I

INTRODUCTION

MJRPOSE

[.lThisHandbookisintendedtoassistDeckofficerswith

their}oadingcalculations.Practicalsolutionsare

emphasized,

and

the

most

common

guestions

about

ship

loading

are

answered

'

L-2

DESCRI

PTION

1.3

-

describes

the

PurPose

of

the

Handbook. There is a

surnmary

of the contents of

each

chapter.Analphabeticallistingofabbreviati-onsused,

a

listing

by

chapter

of

formulas'

and

some

recommended

materialsandequipmentforperformingshiploading

comPutatlons

are

also

included'

1.4

Chapter two, Ship Draft' Trim and Stabitity Notes

-

defines

and

discusses

points

and

practices

which

have

a

practical

ef

f ect

9.,t

saf

e

i:U

economic

ship

loading

'

;

''/

':

_1

.-.

;,',r

'

"

l

More

detailed

ru.4-t

tomes

on

the

of

stabilitY

-

knowledge

may

be

subj

ect

whi-ch

wilI

obtained

from

Published

provide fuller

coverage

,tl

.-=f:

h

?Anl"n

fi"'l,lr#tl='

'


3/109

-2

r.5

chapter

Three, Draft

survey

-

describes

in

detair,

complete

with worked

examples,

the

procedure

for

per_

forming an

fnternational

Standard

Draft

Survey.

1.5

chapter

Four,

cargo

Deadweight

-

summarizes

the main

considerations

when

performing

cargo

deadweight

car_

culations.

Each

step

in

the

procedure

is

then

described

in detail,

complete

with

worked

examples.

1..7

chapter

Five,

Trim

and

stability

-

summarjzes

the mai-n

considerations

when

performing

trim

and

stability

carcu_

rations.

Each

step

in

the

procedures

is

then

described

in

detail,

complete

with

worked

examples.

1.8

Chapter

Six,

Grain

Loading

-

summarizes

the

IMCO

and

SOLAS

requ

j_rements

for

loading

grain.

Each

the

procedure

is

then

described

in

detail,

with

worked

examples.

t

;

;

il

F

q

d

step

in

compl

e t

e

1.9

chapter

seven,

Rolling

period

Test

for

Timber

carriers

describes

the

procedure

for

measuring

the

rolling period

of

a

ship-

This

is

most

frequently

reguired

when

there

is

timber

deck

cargo,

but

is

applicable

for

any vessel

or

cargo-

The

calcurations

to

convert

rorling

period

into

GM

is

then

described

in

detail,

comptete

with

worked

exampres

.

,.ah

r' rl'Tf

&Frt"'

o

ra9lt';-

t

r


4/109

-3

n-lo

Appendix

I,

Prodlems

-

guestions

relating

to

Handbook.

Atl

questions

consists

of

twenty-seven

(27)

the

material

covered

in this

are

worked

out in detail.

d#

vrtnir

il'ffit'i*-


5/109

1-

11

&P

DXSP

WT

F-P

@{

frts

fG

L- J

r

tB

I.cF

I.cG

LXU

tilG

r{Tc

D

@?{

C

SF

Sg

TKU

?FC

VIIH

wlr

E

The

out

-4-

following

abbreviations

are

commonly

used through-

the

text

t

,.-

- After

PerPendiculars

-

DisPlacement

-

Deadweight

-

Forward

PerPendiculars

-

Metacentric

height

-

Transverse

Center

of

BuoYancY

-

Transverse

Center of GravitY

-

Length

Between

PerPendiculars

-

Longitudinal

Center

of

BuoYancY

-

Longitudinal

Center

of

Fl-otation

-

Longitudinal

Center

of

GravitY

-

Longitudinal

Metacentric

Distance

- Center of Gravity from Midship ot'{G)

\-

*-_z

-

Moment

to

Change

Trim

by

One

Centimeter

-

Port

-

auarter

Mean

-

Starboard

-

Stowage

Factor

- SPecific gravitY

-

Transverse

Metacentric

Height

-

Tonnes

per

Centimeter

(Immersion)

Volumetric

Heeling

Moment

Volumetric

Vertical

Moment

Midships

I

,I

I

I

I

I

I

I

I

I

t

-1

---slJ--

fttv''

in

'{*ufr

tE$


6/109

-5

FORMULAS

I.L2

The

followin9,

formulas

are

putat

ions

,

'"

DRAFT

SURVEY

(ChaPter

3)

Forward

Draft

=

Fwd(P)

+

Fwd(S)

2

used in

ship

loading

com-

Aft

Draft

=

llid

Mean

=

Aft(P)

+

Aft(S)

2

Mid(P)

+

Mid(S)

2

2

QM

=

Mean

of

Mean

+

Mid

Mean

Trim

=

Fwd

Fwd/Aft

Mean

Mean

of

Mean

DISPLACEMENT

Displacement

First correct

Vessel

trimmed by the

LCF

is

Fwd

-

you

LCF

is Aft

-

you

Vesse1

trimmed

by

the

LCF

is

Fwd

-

you

LCF

is Aft

-

you

Aft

=

Fwd

+

Aft

_____2-

=

Fwd

&

Aft v@

correction

=

TPC

x Draft

remainder

in

cm.

=

DISP

+

DISP

correction

ion

=

TRII'1

x

TPC

x

LCF x

100

=

corr

for

trim

I,BP

\,

STEI|N

'

\

\

I

SUBTRACT

1

j

ADD

J

HEAD:

ADD

SUBTRACT

'l

1t'Prll6th

eAuu

'


7/109

-6

50

x

l4TC

diff

=

Final

Trim

Corr

econd Correction

Displacement

=

TPI

First Correction

=

=T2*

I

I

I

I

I

I

l

I

I

I

E

I

I

I

I

LBP

{-

Draft

remaining

Trim

x

TPI

x

LCF

x

LBP

1

Second

Correction

=

T'

x

6tr

x

MTI

diff

LBP

MTC

difference

(Metric)

:

(a)

QM

+

50

cm

=

MTC

(Found

from

Ship,s

Data)

{b)

QM

-

50

cn

=

MTC

(Found

from

Ship,s

Data)

MTCdiff=a_b

(a)MTC

_(b)

Mrc

=

MTC

difference

MTI

dif ference

(

f mperial

)

:

lild*


8/109

-7

CARGO

DEADWETGHT

(Chapter

4)

cargo

DWT

=

Drsp

cotrectea

for density

(2nd

condition)

(minus)-

TorAL

weight

deductions

(2nd

condition)

=

NETT

displacement

(

2nd

condition

)

(minus)-

NETT

displacement

(lightship

=

1st

condition)

=

CARGO

LOADED

PERCENTAGE

(?)

=

Hold

Capacity

x

Total

Capacity

DEFLECTION

=

MID MEAN

-

FWD

&

AFT

Hoggi-ng

=

MfD

MEAN

-

FWD

&

AFT

Sagging

=

MfD

MEAN

-

FWD

& AFT

100

MEAN

MEAN

MEAN

AFT

MEAN

ven

Keel

=

MfD

MEAN

=

FWD

MEAN

=

TRIM

FORMULAS

(Chapter

5)

LCG(FP)

=

LBP

+

MG

'':

--,

t,

t7r.

-z-

MG

is

Aft

-

you

ADD

MG

is

Fwd

-

you

SUBTRACT

LCB(FP)=LpB+LCB

2

LCB

is

Aft

-

you

ADD

LCB

i_s

Fwd

-

you

SUBTRACT

Longitudinal

Moment

= Weight x

LCG(Fp)

New

LCG(FP)

=

Total

Longitudinal

Moments

TriM

LCVCr

=

LCG(FP)

-

LCB(FP)

TRIM

=

MTC

ub

.^{er1W

af

{Vtrfir

T|alrr

IltrEtltp

'fnLrhldF

,r,


9/109

_B

Final

Longitudinal

Moments

=

DISp

x

tCG(Fp)

Longitudinal

Momenfg

of Constant

=

Final

-

all

other Longitudinal

Moments

LCFG(FP)

of

the Constant

=

Longitudinal

Moment

Change

of

Draft

=

Trim

2

=

+

Weight

TPC

x

MTC

TPC

Weight=TPCxTrim(cm)

2

Vertical

Moment

=

Weight

x

KG

KG

=

Total

MoqenI{ll

-

Totat

Moments(S)

Mean

Sinkage

Di-stance

-

2

Rise

of

G due

Where:

New

KG

=

O1d

KG

=

Total

Change

in

Moments

GM

-

TKM

-

New

KG

*GG1

=

Total

fnertia

-

Total

IrJeights

G1M=GM-GGt

Rolling Period (

Imperial

)

0.448

Ft

tffi-oF

crq

to Free

Surface

=

(

Metric

)

0.797

BB

Metres

Vsq.rt ot

cM

Lx83xsg

L2xDISPxn2

,

**oo*d

,-z

t'

\

-.{$-

Yv'

L

=

Length

of

tank

B

=

Breadth

of

tank

Sg

=

Specific

Gravity

n =#ofLongitudinal

is

divided

of

liguid

in

tank

compartments

into

which

the

tank

Total

Weights(

P)


10/109

-9

RoLLTNG

PERrop

fEST

(

chapter

7

)

(

TMPERIAL

)

GM

=

0.1936.x

82

--r--

(

METRIC

)

f

=

Rolling

B

=

Breadth

GG,=wxdKG

-

.

DISP

Where:

Where:

GG.

I

DISP

W

w

dKG

GM

Where:

W

GoGt

Weight

Distance

from

water

line

cot.O-

=

Angle

of List

GRAIN

LOADING

(Chapter

6)

HHM

=

VHM

SF(

cargo

)

=

VHM

blsP

x

sF

CUBIC

METRES

(U3)

=

Cubic

LONG TONS

x

1.016

=

Metric

Tonnes

(Mr1

D

GM

=

0.6532^x

S2

T-

Period

in

of

Ship

Seconds

of

time

Shift

in

Centre

of

Gravity

W

+/-

w

Original

Displacement

Weight

to

be loaded

or

discharged

Distance from

KG

to

G

of

weight

WxDxcot.0-

r

Feet (

35.315

^dLfi

u

thGfl

-^fi

v

Y'*-


11/109

-10

NECESSARY

MATERIALS

f.13

Work

Forms

atre

recommended

to

ease

the

culations.

Several

forms

are

included

the

examples in this

Handbook.

These

as

is,

or

altered

to

suit

personal

or

requirements.

work

of

cal-

as

part

of

may

be used

operational

calculator

wilI speed

up calculations.

Any

r.14

stability

Booklet

and Loading

Manual,

complete

with:

-

hydrostatic

and deadweight

tables;

grain

loading

plan;

general

arrangement

plan;

capacity

p1an.

and

1-

1s

-

tank capacity

plan

or manual.

These

items are all supplied

by the

shipbuilder to

the ship and should be studied with

care.

Certified hydrometer

and

water sampler (water thief).

These

are used to

measure

the specific

gravi-ty

(Sg)

of the

water in which the ship is floating. A

special

hydrometer for measuring the Sg of fuel

and

lubricating

oils should also

be

available.

A seunding tape

for measuring tank contents,

and

a

standard tape for

measuring

ho1ds, lockers, and other

1.16

L.L7

spaces.

A

good

of the

program

I

better

scientific

calculators will

have

a

for

integration

by

Simpson,s

Rute

-^.,f\av4f

-

u-1n'

-.ftfu

\'

W

I

I

t


12/109

PL}ISOLL

MARKS

N

I

IJ

I

r,t

00I.t

E

E

$

o

ctl

td

J

g

{

F

tf

u

n

pa

t

LI

v.

L -

Ez

-l

@

cr)

rl

rl

Figure

1


13/109

NAFT

{ARKS

E___

a-88t*

?O cm

6-60

crn

5O

cm

{-ro

cn

30

cm

2-zgcm

lO

cm

}IETRIC

N

-12

HOI.I TO

READ

I{ETRIC

DRAFT

I,IARKS

(METEFS

and

CENTIMETERS)

LAH

9M

BH

7tl

6tt

l(

I

a

I

E

U


14/109

_

13

TMPERIAL MEASURE

IO?

OF

SECOI{D

DECK

'TRINGER

PTAIE

DEADWEIGHT

9722

TONS

FREE

EOARD

DRAFI

z5'.lor|t

Fign:re

3


15/109


16/109

The

weight

bottom

growth

is

the

rnost

difficult

to

allow for.

fb

is

frequently

significant,

and

value

)

of 50 kg/u'

has

been

suggested.

A

check

of

the fouring

exposed

when

the

vessel

is

light

can

be

helpfur.

A

bottom

survey

by

a

quarified

diver

provides

the

most

accurate

data

2.5

one

apparent

change

in

constant

must

be

guarded

agai.nst.

A draft

survey

at

anchor,

or'aiongside with

one

anchor

down,

wi-rI

be

minus

the

weight

of

the

anchor

and

chain.

If,

at

the

discharge

port,

both

anchors

are put

on

the bottom

whi].st

alongside,

the

difference

between

the initial

and

final

surveys

wilr produce

an

apparent

increase

in

the

weight

of

the

cargo

out_turn.

-

15

2-1

2-6 Ensure the weights of anchors and chains

are

added

or

subtracted

from

the

loading

and

constant

calculati-ons.

SPECIFTC

GRAVITY

2-7

Specific

gravity

(Sg)

is

ratio

of

properly

unloading

I

I

I

I

I

I

I

I

I

olume

of a

substance

compared

:l*"

vgIume

of

distilled

water.

of distitled

water

is

1.000,

the

1.025

times

as

much

as

one cubic

(fresh)

water.

Therefore,

a

ship

Iess

sea

water

than

fresh

water.

the

weight

of

a

given

to the weight of the

The

theoretical

Sg

Sg

of

sea water

is

meter

of

distilled

wil1

displace

L.025

I

I

I

vnt'ot

{ou'o*dtr


17/109

-

t6

A-t

The

actual

Sg

ig

always

changingr

particularly

in

the

_lrarbour.

The

effect of tide water

and

rivers is

such

that

constant

measuring

of the

sg. is

reguired

through-

out

loading.

rn

some

harbours

where

the

effects

of

sea and

fresh water

mixing

are

extreme,

it

is

necessary

to

measure

Fwd, Aft,

and

Midships

Sg,s,

dod

use

the

average for

Draft

and

Deadweight

calculations.

It

may

be

necessary

to get

measurements

for both

port

and starboard sides

of

the ship if

maximum

accuracy

is reguired. Measuring

the

Sg

at different

depths

2-9

2.

t0

may also be reguired.

Use

a

partly

stopped,

weighted

container

and

a

Iine

equal

in

length to

the

distance from

the

deck

to the

kee1, to sample the water for Sg measurement.

Drop

the container into

the

water and withdraw

it

at

an

even

rate.

Witi:

practi-ce,

the

container will

be

j

ust

filIeo

as it

breaks the

surface.

Water

samples

collec-

ted

in

this

way

will

represent a

good

average

of the

water in which

the ship is floating.

Sg

measurements

for

Draft

and

Deadweight

surveys

must

be

made

with a certified

hydrometer.

DENSITY

AND

TEMPERATURE

2.11 A

great

deal has

been written

regarding

the

effect

of

temperature

on

density.

This

is

important

when


18/109

L7

consideratign,

or

when

specific

gravity

sclentl-f

ic

calculat

ions.

2.L2

However,

in draft Burveys,

it

is

unnecessary

to

measure

the

tempetature

of

the river,

lake,

or

oeean

water

in

which

the

vessel

is

riding.

The hydrometer

reading,

if

taken

as

Eoon

as

the sample

is

drawn,

will

include

the tenperature'

as welr

as the salinity effect

on

specific

gravity.

A

GOLDEN

RULE IS,

THEREFORE,

MEASURE

THE

WATER

TEMPER-

ATURE IF YOU

MUST, BUT

DO NOT

USE

IT

IN DRAFT

SURVEY

CALCUTATIONS.

The Slnka

and

Trlm

caused

b

Currents

and

Ti

dal

.-.

y*l_"__g9jtt-v

r-"Lu

is

reguired for

slml lar.

Host

seafarers are

well aware

of the

effect

known

as

"squat"

whlch

causes

ships

to

tncrease their

draft

when

traVelllng

at

speed

in

shaTiow

water"

U g _ hey

may.

not 6e

aware

of

is

that

a

ship

mooFef

br

anchored

in-'sliallow

water

expeilences

the

same

effect

when.

there

is

a

';ldat

stream cr

current

running. The

cause

of

both

effects

ls

{t,

-,i,,

,L-

-Y:..

r , t)

'.-1

Y

r


19/109

-

L8

Piccr

ol

Gr?d

rith

9rn

throslh

crolrt

F'igure

Frrlrklr{

rlcltoa

ol

reuel

rloajridr

E.

Stokoe,

lleight/Volume

Relationshlp Requlred

for

Draft

Suive

pp.15r17.

The

Bernou'lli

effect

can

be

ddmonstrated by

trying

to

blow

a

piece

of

card

off

the

end

of

a

cotton

reel

(Figure

5).

It

is

,impossible

to

blow

the

card

off.-

The

high air

ve'locity

on

the

inner

face

of

the

cartl-

causes

a

Toqal

drop in

pressure

rtTafiG

-To

the

outbr

face oT t 'e

card, thus

keeping

it

firmly

pressed

on

the end of

the reel.

Berhouili's

equation,

which

governs

this

effect,

is

P

+

p

2

+

Pgh

=

constant,

where

P

ls

pressure'

Z

p

the

water

density,

v

is

the

velocity,

and h the

dePth

of

water.

C'learly

dsi

v

,increasesn

at

a

given

water

depth'

P

must

dlcreas6

for

the

equation

to

remain constant.'

Aclurl

drttrclron cutra

-

---/

;-.-,-..".-.-

a

Fisr:re

6

^t"-to,'5,t:f

t"'-

-"t-vt

{ou*"as

.

Yo''


20/109

-19-

fh*q-

amount of

sllkage

gaused

by

thls

effect

wlll

dlpCnd,'therefore,

o-n

the.lrater-vefoslW;

il ;iii

also

depe4q gn

tle

depth

ofTatdr

beneath

fie

fEEf

qrq-tTe

shlp,s

length.

The-slnkage

fn

some

cases

nlll be

conslderabl-e.

For

example,

a

11600

ionne

coaster mobred

ln

a

rlver

where

the

clrrent

ls

runnlng

at

4

knots

nlll

experlence

a

slnkage

of

at

least

5

cm uhere

there

ls

about

0.35

m

df

watir

under

the

keel.

tt

ls

therefore

deslrable

to

ualt

untll

the depth

of

water

under

the

keel

ls

as

large

as

posslble

before

measurlng

draughts

lf

there

ls any

current.

Clearly

ln a

tldal

stream

lt

r*ould

be better

te

measure

the

draughts-

at

slack water

thus

avoldlng

thls

slnkage

effect

lf

at all

posslble.

{lth

data

curreqtll

avallable

lt would

not be.posslble

for

the

slnkage-

llkely

to

be

experlenced'to

be

estl-

mated

ln

all

cases.

An

approxlmate

theoreilcal

i:iltil:,;'1,H,111iJiilSBlffi"f

'f.,:lJlJ;:',1:

Sqgq

of Full

Form

Shlps

ln

Shallow

l{atir,

fhtffi

fdf.ft5'-197f

DISPLACEMENT

AND

DEADWEIGHT

2.13

D1s-placement

.-is

t-he weight of

water dj-splaced by the

ship

which,

for a floating

vessef, eguals

the

weight

.of

the

ship.

i l-ght

Ship

'

s

weight

plus,)

Deadweight

equals

Displacement

(DISP).

2.L4)

Deadweight

is the total

weight

carried by

the sh-ip.

Included in

deadweight

are: cargo, constant and stores,

fresh

water,

fuel and

ballast.

SHIP STRUCTURE

A11 vessels

must

be

able

t.o

kinds of

minor

collisions

remain afloat after certain

at sea,

or

if

damaged

by

^

*-

H

.ft6rtvt}

I

.,-i(l' "

\

2.L5

w>


21/109

_20

heavy

seas.

Watertight

bulkheads

are

one

of

the

major

structural

iteqs

built

into

the ship

for

this

purpose.

The

number of these

bulkheads

is

regulated

by the

length of

the ship

2.L6

Four

i-s

2.16.1.,

/'

,/

2.t6.3

the

usual

minimum

number

of bulkheads

required:

A

collisj-on

bulkhead

placed

at one-twentieth

(I/20)

of

the

shiprs length,

measured

from

the

stem.

A bulkhead

forward

and

the

engine

(and

boiler,

if

steam

powered)

space

An afterpeak

bulkhead

positioned

to

enclose

the shaft tubes

in

a

watertight

compartment.


22/109

-2r

CMIP

STRUCTURAL

STRESSES

l,-17 A

ship

ported

2.L7

.L

e

is

considered

a variabty loaded,

variably

sup_

beam,

for

strength

analysis.

That

is:

The

weight

of

the

ship,

its

eguipment

and

cargo,

will

vary

meter

by

meter

along

its

length.

2.17.2

The

ship

is

supported

it floats.

fn

stitl

support per

meter

at

bow

because

the

ship

is

by

the

water

in

which

water,

there

is

more

the

stern

than

at

the

fuller

aft.

2.L7.3

rn

a sea

there

is more

displacement,

and

there-

fore

more

support

or

upward

force,

dt

the

crest

of a wave.

There

is

less

displacement

and

therefore

less

support

in

the

troughs.

2-18 The

major

stresses

are:

longitudinal

tension

(or

stretching),

compression

i-n

the

deck

and

keel,

dDd

shearing

forces,

ds

shown

in Figure

7

.

2-L8-1

when

the ratio

of

weight-to-support

is

greater

at the

ends

than

amidships,

the ship

"hogs,,

.

The

keel is

in

compression,

the

deck

is

in

tension,

and

the

ship

bends

upward

in

the

middte.

\^^t$

1frcttq^

l

I

t

I

I

t.xr2

I

I

I

I


23/109

-22-

When

the

ratio

of

weight

to support

is

amidsfips than at the ends, the

shi-p

The

keel

is

in

tension, the

deck

is

in

sion,

and the

ship

bends downward

in

the

",

rlF

0x-ltgr"

'

2.]-8.2

I

greater

i-

FJ-.t

"sags".

\=_/

compres-

middle.

L\

f-

-,

l.\.-

lJir,

'

2-19

Since the

keel is

constructed

with a heavier

weight

of

metal, the deck is

where almost

all failures

occur.

The deck of a cargo

vessel is further

weakened

by

hatchways and

other

necessary

openings.

These

openings

must be

reinforced.

Sharp corners

tend to

concentrate

stresses,

So hatch

corners

reguire

special

attention.

2.2O

The

deck

is

subject

to

other stresses

such as

deck

cargo

and

the

weight

of

water

when

heavy

seas are

shipped.

Since deck

beams

must be

cut out at

hatch

coamings,

the

load

bearing strength

is reduced. The

weight and

placement

of

deck

cargo and the effects

of heavy seas

must

be carefully

considered.

The

deck

plates

should

be

strengthened,

if reguired. Hatch

coamings

should

be

checked

for strength

and rigidity

I,ONGITUDINAL CENTRE

OF

GRAVITY

2.2L

The

longitudinal

centre

of

gravity

(

;b

)

of a

ship

is that

point

along

its ,.nnln

where

oJ"-nulf of

all

weights

are

forward,

and

one-half

aft. That is, it

is

the balance

point

for

the ship

and

its

contents.

b

,t

-tr

\t

{r'9hN4r

r-


24/109

I

I

I

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I

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I

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ur

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ur

ul

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ut

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a/1

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Fn

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trl

L

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25/109

F

{

u

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n

u

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F

z.

trJ

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rr

l

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=

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tn

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o

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Figure

B

uv'ln3loN3du3d

'rJv


26/109

F

H

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ul

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u

LJ

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I

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fi

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ro

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tf,

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r

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rncrr'"gr

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Figure

9

rtrrtrtqN3du3d

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27/109


28/109

rd

(J

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1-

EXAHPLE.

SOUNDING

AT

B.sIH

s.G.

0,994

?

VIJL.=31.3M

o

K6=0.?6H

INERTIA=109.4H4

06=40.06

Figure

l-6


49/109


50/109

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Figure

19


51/109

GEilERAL

t3-I

lThe weight a ship can carry varies considerably with

location

and

season.

..More

can

be

loaded

in

Trop

countries,

but

less

in a

Summer

Season

Zone'

Seasonal

Winter

Zone

loading,

when

applicabl-e,

is smalfer

still'

rstudy

the

Loadline

certificate

carefully

to

avoid

con--

flict

between

the

ship

"1d

the

Port

Authorities,

or

with

lh.shipowners.AFreeboardTable..(Figurel)ispro-

vided

in the

Ship

Stability

Manual

'

CHAPTER

FOUR

CARGO

DEADWEIGHT

such

as

fresh

water,

fuel

oil,

lube

oi1'

,

necessary

for

the

intended

voyage,

must

when

calculating

Cargo

Deadweight'

',Make

adjustments

for

re-supply

if

a

call

at

a bunkering Port is

regui-red '

If

supply

is

much

larger

than

projected

consumption,

less

Cargo

Deadweight

may

be

carried.

t

R

=(

vl

{l

tr

\-

IU

Y1

a

I

L

4-3

Consumables,

ball-ast,

etc.

be

considered

4.3.1

4

.3.2

CARGO

DEADWEIGHT

CALCULATION

7.n

;Carculating

the

cargo

Deadweight

Availabre

is

relatively

simple.

consult

the

Freeboard

Table

f,or

Draft

and

Dj-s-

placement al-lowed.

subtract

Lightship

weight,

constant,

Ballast

and

Consumables.

The

remainder

is

Cargo

Deadweight

Available.


52/109

-

51

E,KAMPLE:

For

a

s5-mple

vo1fuge

with

a

through

a Seasonal

Winter

Timber

Winter

DisPlacement

Displacement

Lightshi-p

Weight

Constant

Ballast

Fresh

Water

Fuel

Oils

CARGO

DEADWEIGHT

AVAILABLE

CONSUMABLE

CONSUMPTION

Timber Cargo, in winter,

Zone

-

5

u

\1

s

{

tjr

-.-

3-

U

R

*/-

I

L

I

I

I

I

I

I

I

I

I

I

I

t

-

8.819 MT

Draft

=

21654.000 MT

=

-434L.000

MT

rJSfTloTT rqr

=

-L96.000

MT

17

717

.

000

-265

1.000

lZZ

6E

.TTI-

-308.000

TaTSE

-To-0

-696.000

L3462.000

4.5

If

oil-

and

fresh

water are

to be

replenished

at

an

intermediate

port,

the

cargo

Deadweight

may

have

to

be

reduced.

If

the

planned intake,

plus

the

fresh

water

and

fuel

remaining

after

passage

to

the

bunkering

port,

is

greater than

the

consumables

on

board

at

Final

Survey, the

difference

must

be

deducted

from

cargo

Deadweight

Available.

MT

MT

MT

MT

MT

MT

MT


53/109

EXAMPLE:

Fresh

FueI

Total

Length

of

voYafe

Water

Water

Consumables

-52

to

bunkering

port

=1

=

carried

if

a shiP

a

Seasonal

Winter

6.5

days.

150

MT

+660

MT

B1O

MT

132

MT

+396

MT

\

q(

u

\A

N

t-

\

\,

2

ri

R)

tL

Fresh

Water

GonsumPtion

@

B-0/daY

Fuel

OiI

Consum,Ption

@24-OldaY

x

Total-

ConsumPtion

Balance

of

Fuel

and

Water

Left(810-528)

Planned

Intake

-

Fresh

Water

-

FueI

Oil

-

Total

Balance

of

Fuel

and

Water

Total

after

RePlenishment

Consumables

at

Port

of-

f,eqilg

Di-fference

of -AA

The

72

MT

must

be

deducted

from

Port

of

Deadweight

Available.

SEASONAL

ZONES

x

16.5

=

16.5

=

528

MT

=

282

MT

=

200

MT

=

+400

MT

=

600

MT

=

+282

MT

=

882

MT

=

-BL0

MT

=

72

MT

Lading

Cargo

/'

4

.6

Less

Zone

EXAMPLE:

cargo

may

be

and

wilI

enter

loads

in

a

Zone.

Summer

Summer

Timber

Winter

Timber

Difference

Loadline

Loadline

9.07

|"1

=

22336.00

MT

8.819M=2L654.00MT

=

642-00 MT


54/109

Y^;'

l^,e

1r^,

ul{rs

-5:

1.7

r

The

weight of Consumables

used

in

the voyage

from

port

of

lading to

the

ldinter

Zone may

U"G-Od"]

to the

winter

\./

Zone al1owab1e

displacement

when

cal-E[fating

allowable

Cargo

Deadweight.

l.B\

If

the ship

is to

take

on

consumables

at an intermedi-ate

J

bunkering

port

in the

Winter Zone,

the total

planned

weight

";

consumables

on

board at

that

port

wil-1

govern

the

allowable

Cargo

Deadweight.

LOW

DENS]TY

CARGO

t_

r1 -

t

t

*

F

]

t

I

I

t

'l

\

C-../

Lr\

.tr

F

.9

Total

Cubic Capacity

of the

ship is available

Capacity

P1an.

Bale Capacity

j-s

used if the

cargo

is

not

grain

or

other bulk

commoditi-es.

EKAMPLE:'

Load a

fuJ-I,

homogeneous

cargo

with Stowage

of

65

0F/LT.

conversion

- I

rt3/LT

=

o.o2grz u3/ut

??

1 MJlMT

=

35.3145

Ft'/LT

Therefore

sF 65

r't3/."O

0.023L7

=

t./s06050

Bale

Capacity

=

19183-82

M3

Weight of

Cargo

=

Bale Capacity

SF

=

19183.

B2

---i150-

=

12789.273

MT

in the

booked

Factor

i

\r

F

-

.lp

^\

e

u3

/vr

NOTE:

A

number of

good

books

on

cargoes

and their

Stowage

Factors

are

available. "sTowAGE

-

THE

PROPERTIES

AND

STOWAGE

OF

CARGOES*,

by

Captain

R-

E.

Thomas,

is

a

particularly

complete

reference.

I

I

il

il


55/109

-54

CARGO

DISTRIBUTTON

4.

10

,z--.-:

a

The

q15g9 conslderation is to distribute cargo

so

that

weight

is

evenly

spread

throughout the

ship.

4.10.1

If

Weight-to-Flotation

is

greater

at the ends

of

the ship than in the

middle,

the

a"g {]

deflect

up.

This is called

"Hogging".


56/109


57/109

(3)

Order

is to

Hold

No.

l-

Hold

No.

2

Hold No- 3

Hold No. 4

-56

carry

16,000

MT

l-6000

x

.19l-B

l-

6000

x

.27

60

l-6000

x

.2758

16000

x

.2564

TOTAL

Cargo.

=

3068.80

MT

=

441,6.00

MT

=

4412.80

MT

-

4LO2.40

MT

=

16000.00

MT

q

\(

$

$

F

\

Lrl

\

IU

)

.t

_-P

4.17 The percentage of cargo per hold calculation will

often

produce

a concentration

of

weight

j-n

the

middle.

This wi-11 cause Sagging. This can be minimized

by

shifting

some

weight forward.

4.18

)

rn"p".tion of the

calculated results, and rounding

--/

to

100

Metric

Tonnes, wil]-

give

a

good

approximation.

EXAMPLE:

NOTE:

If the ship

has Tween

Deck

Ho1ds,

cargo space

as demonstrated.

solve

for

each

4100.00

MT

4300.00

Mr

4300.00 MT

3300.00

Mr

to avoid overloading.

the

Midships Drafts.

reason, a

Draft

and

Hold No.

4

Hold No. 3

Hold No.

2

Hol-d No. 1

4L02

.40

4412.80

4416.00

3068. E0

2.40

112.80

1 16.00

23L.20

TOTAL

4.19

4.20

=

16000.00

MT

The

best

practice

is to

part

load each

hold in rotation.

Deflection

and Trim

can be checked

as loading

progresses.

Draft must be

watched

constantly

Tli.s

gan be done by checking

If

loading

is critical- for

any

Deadweight

Survey must

be done.


58/109

I'

il

$

$.l

tr

\il

[r

\

F,

I

dti

':

i

rli

Ili

,il

II

IH

ti

ig

rlfi

li

tl[

rll

l

*

il

:t

t;

ri

t

rl

il

il

tl

r_f

M

{

TJ

n

:l

n

i-J

Z.

LJ

t5

fl

=

rl

I

LL

n

Lf

v

Lf

Z-

F]

Z.

L-

:E

u?

u)

ll

tf

+

a

Fl

ll

\o

Y

=

t4

+

Fl

ll

(t

+

u

F{

[.

ul

v

:E

U?

E

q

(,l

tl

=

c?

\o


59/109

CHAPTER

FIVE

TRIM AND STABILITY

GENERAL

/

5.1

)

Trim and Stability calculations are mainly a matter

J

of

correctly

interpreting

pians, tables,

a.ta

graphs.-

ship

stability

and

Tank manuals

provide

va]ues

for

Longitudinal

Center

of Gravity

(

LCG

)

,

Transverse

Center

of

Gravity

(

KG)

,

Moment

of

Inertia,

and other

data

necessary

for

ship

loading calculations -

5.2

This

data

may

be

j_n

graph

form

(Figure

14), or tabul-ar

(Figure

16).

Tabl-es

are

more

common,

and are

easier

to

work

from.

/'^

(S.:)

Lonqitudinal

Center

of Gravity

can be calculated

from

\./

'--/

the

Forward

perpendicular

(LCG

FP),

the After

Perpendic-

ular

(LCG

AP),

or

from

Midships

(MID)-

Carcurations

of

LcG

from the6p)are

shorter,

and avoid

dealing

wlth two

sets of

longitudinal

moments.

This

greatly

reduces

the

chance

of

error,

so a1I

our

examples

will be

based

on

LCG

FP.

The LCG

of

a

hol

d

is

assumed

to

be at

the

longitudina]

center

of that

hold.

The

LCG

of

uniformly

distributed,

homogeneous

cargo,

such

aS

grain,

is

also

at

the center

of

the

hold.

5

\{,

+

\0

r

\

It

U

R

\t

,{.

q

5.5

',,

S.l

If the

hold

is

to

be loaded

with

mixed

cargo,

then

an

LCG

is assumed

to

be at

the

center

of

each

type

of

cargo.

5.7

I

For

or

special cargoes

such as

heavy

machinery,

the center

gravity

information

should

be

supplied

by

the shipper.


60/109

-59-

"t'-

F{

\ r,

U

\

$

L

\

t{,

L

V

;5

di-

IRIM

CALCULATION

(

t't)

The

r.cG

,method;is

the.*.most

accurate

for calculating\--l the trim of a ship, i""u,r";

Jr

thfi.J

";-#;""

;Tfi;

ffi-the;h$]

inctuains

buoyancy,

are

consid_

ered.

5'9

'

llt

from

the

Forward

Perpendicular

Lcc

(

Fey

is

egual

to

one_ha]f

of

the

Length

Between

perpendicu.l_ars

(

LBp

)

pf

us

or

mj_nus

The

Center

of

Gravity

From

Midships

(MG).

LCG

(FP) =

LBp

--7- +

MG

5

.9.

1

If

MG

is

Af

t

,

it

i_s

added.

5.9.2

If

MG

is

Forward,

it

is

subtracted.

5'

10

Tht From

the

Forward

perpendicular

LCB

(Fp)

is

egual

to

one

half

LBp plus

or

minus

the

iongitudinar

Center

of

Buoyancy

(tCB).

LCB

(FP)

=

LBp

__T_

+

LCB

5.

10. 1

If

LCB

is

Af

t,

it

i.s

added.

5

.I0

.2

If

LCB

is

Forward,

it

i_s

subtracted.

5

'

11

The

Longitudinar-

Moment

of

everything

aboard

the

ship,

whether

Cargo,

Constant,

Consumables,

or

Bal1ast,

is

the

Weight

times

the

LCG

(

Fp)

for that

cargo.

Longi_tudinal_

Moment

=

Weight

x

LCG

(

Fp

)

5-12

The

Lcc

(Fp)

changes

whenever

cargo

is

loaded

or

unloaded,

supplies

are

taken

or

consumed,

and

bal_1ast

tanks

are fil1ed

or

discharged.

The

new

LCG

(Fp)

is

equal

to

the

total

Longitud_

inal

Moments

divided

by

the

Displacement.

T-ful3x::l'&"/

lrdc

I

I

I

I

il

il

il

fl

Az.ut/ LcA

(fp)

DoV/*"--"'--7


61/109

s.13

5

.12

.1

5.12.2

5.13.3

-60

Cargo

,unloaded,

ballast

discharged,

and

suppliEs

consumed

are subtracted.

Cargo, ballast,

and supplies

loaded

are

added.

Trim Lever =

LCG(FP)

-

LCB(FP)

If

the

Trim

Lever

is Positive,

that is,

if LCG(FP) is

greater

than LCB(FP),

the

ship

j-s

trimmed By

the Stern.

If

the

Trim

Lever is

Negative,

that is,

if

LCG(

FP)

is less than

LCB( FP)

,

the

ship is

Tri-mmed

by the

Head.

If the

Trim

Lever is Zero,

that

is, if

LCG(

FP) equals LCB(

FP)

,

the

shi-p

is

on

an even

keel.

5

$:

{.

\J

F

\_

t\

i'1

u.

\

-\L

ew

LCG(FP)

=

Total Longitudj-na1

Moments

Displacement

The Tri-m Lever

is

equal

to the

LCG(

FP

)

m

j_nus

the

LCB( FP)

.

, ,r-

-.--,

/(,:9

Trim

=

Tri-m Lever

x

Dispiacement

MTC

LCG(FP)

OF

THE

CONSTANT

5. 15

It is

best

practice

to solve

for the

LCG(

FP)

of

the

Constant

after

each

Initial

Survey of

the

Ship's

Light Condition

(Chapter

Three).

An

average

may be

used, unless

an

unusual

amount

of

stores

has

been delivered.

e

s.13.2

Trim is

egual to the

product

of the Trim Lever

and

DispJ-acement,

divided by the Moment to

Change

Trim

by

One

Centimeter

(MTC).


62/109

61

-

5.16

The

LCG(FP)

of

the

Constant

moves

fore

and

aft'

depending on Ln" Iocation

and

weight

of

crew

effects,stores,andalltheadditionalweights

that

tend

to

accumulate

over

the

service

].ife

of

a

shiP'

5.:

Tltisofinteresttocomparetheworkformsgiven

in

Figure

11

and

Figure

19

'

The

procedure

used

in

the

example

is

the

reverse

of

the

procedure

used

in

Figure

11

'

The

LCG(

rP)

of

the

constant

j-n Figure 11 is

200'42

M' which

was

the

average

for

that

shiP'

EXAMPLE:

(

see

Figure

11

)

Fromlnitialsurvey'ChapterThree(Figuresll

and

19):

I

I

I

I

I

\

N

\$

*.

v]

F

.\

u

'\

v

\b

$

\

DRAFT

DISP

LCB

MTC

CT

(1)

Trim

Lever

(2)

LcB(

FP)

(

3)

New

LCG(

FP)

New

LCG(

FP)

Since

the

shiP

is

is

Aft

of

LCB(

rP)

3.5326s

803s.5

3.01-

LB2.

l-

1.773

Trim

x

MTC

DISP

=

L77.3

cm.

Jr,,-'

L'arY

D'


63/109

I

(4)

-62

Final

Longitudinal

Moments

=

l=

it

DISP

x

LCG(

FP)

8035.5

x

69.01

5545

29

.85

q

\


64/109

:9

-63

For

practical,

purposes,

because

the distance

f

rom LCF to frl-Asnips is so small in relat

j-on

to the length of the

ship,

LCF

is assumed

to

be

mj-dships. Therefore,

change of

draft is

calcu-

lated, with sufficient

accuracy, ds

trim divided

by two.

fr

{

,u

F

\

V

:-

E

a

\

_

Change

of

Draft

=

Trim

-T-

5.2L

Mean Sinkage

is equal to weight

divided by

TPC.

If weight is added, the

mean

sinkage is greater;

if the

weight

is removed, the mean sinkage

is

less

Mean

Sinkage -

+/-

Weight

TPC

NOTE:

TPC here

is the

final

TPC. That is, the

TPC

for

the

final

loaded condition.

5.22

The

weight

i-s

placed

forward of the tipping

center

to increase the

forward

draft; it is

placed

aft

of the

tipping

center

to increase the

after

draft.

5.22.

1-JThe

weight

required is egual

to TPC times

.

the tri-m

in centimeters

divided

by

two.

t.

\'

-l'

*

/

.\

weight

=

TPC

x TRrM

l

lL',

:-

{"'

'

--T-

I

r'"'

5.22.2

The

distance

to

locate the

weight

is

two times

the

MTC

divided

by the

TPC-

i ,\-

-fi]/

-{

rri r

Distance=)

xMTC

\Y\ri\'-

r

fi'

i

'l

{:

e'

iL

*\

\t(

''

. \Y\'

:

1

{,

'

\

f

I'

,t

TPC

EXAMPLE:

A vessel,

trimmed

by

the

on an even

kee1.

Fwd Draft

=

8.36

M

:""

=

27

t

1?t'

;'

f

':-1"

stern,

must be

put

Aft Draft

=

8.46

M

MTC

=

233


65/109

I

il

l

(

-64

-r

ttc

f

'*

27 x

(8.46

,n,a {rpn^,

t,'

/

i'i,i

/

'/

'isrt

tt

f

l(

ll

,C

r'le+er-t

i."^

k,:

'.ln*,

lh'

I

1-r

2

rttfc

Distance=2x233.0

---zT-=

TF.

A

weight of 135

. 0

t'4/T

of the

tipping

center.

STABILITY

CALCULATTON

FORMULI

8.36

)

100

,'=

135.

O M/T

17.26 t{F

placed

17.26 1"1

forward

Weight

(

*

h

s

\t'

F

\

,\t,

Yl

*

d_

5.23

It

is

the

responsibility of an office to

always

maintain a stable ship, in order to protect Iives,

the ship

and its cargo;

5.24

Stability

calcufations

are the most important

aspect

of the

loading

calculations.

Not

only

the crewrs

comfort

but stress

on a shiprs

struc-

ture is

affected by

stability, .ld

a ship in

_1 aUfe

equilibrium is not so

liable

to capsize.

5.25

Transverse

Stability j-s a subject all

Deck

Officers

are

familiar

with,

so

only

the

main,

practical

points

are summarized

here.

5.26

The following

forrnuli

Transverse

Stability.

are

used

in

calculating

Vertical-

Moment

=

Weight x KG

New

K'G

=

ol-d xc

ltotar

-Ctran{"

i"

vo*.;?

.GM

=

TKM

-

New

KG

lii

ii

i

I

I'

ti

i

1,

,i

il

;

GGt

=

GM

=

Rolling

Total Inertia

-

Total

Weight

b

L

t'

GM

-

GGt

Period

(

IMPERIAL)

=

0.44B

(

feet

GM

0.7978

(meters

)

sg.rt

G

M

n

.771

b

.-

\ 6r'4

Rolling

Period

(METRIC)

Where

B

=

Breadth of

Ship


66/109

-

65

FREE

SURFACE

EFFECT

5-27.Full or empty tEnks have no free surface, since

there

is

no

liquid

moving

as

the

ship

rolrs

in

the seaway.

fvoid

slack

tanks

to

the

greatest

extent

possible

to minimize

the l-oss

of

GM

caused

by free

surface

-s.

id'i

rn

a heavy

seaway,

the

liquid

in

a

sr-ack

tank

will-

surge

with

considerable

speed

and

force,

sometimes

causing

damage

to the

tank

itsel-f.

5.29

Fuel

oil tanks

are

normaJ-ly

only

f

i]l_ecl

to

B 0

or B 5

percent

capacity

so

as

to

a.,,oid

overf

low

oil

polluticri.

Fresh

wei-er

anc fuel-

are

bcth

subject

to daily

consumption,

so

it is

impossible

to

keep

these tanks

fu11

for

the

entire

voyage.

Dividers,

or swash

plates,

can minimize

the free

surface

to

a

large

extent.

5.30

Sea water

ballast tanks shou]d be either filIed

to their l-imit,

or

empty. When

filling

these

tanks, it

is

good practice

to let

them

overf

l-ow

sufficiently

to ensure

no

air

pockets

are

trapped

inside

-

5.31

available,

f

or metri-c

Ri-se

of

G

due

to Free Surface = L x 83 x

SeLr

l2

x

DrsP=-zI

v

Where

L

=

Length

of Tank

B

=

Breadth

of Tank

Sg

=

Specific

Gravity of Contents

n

=

Number

of Longitudinal

Compartments

into which

tank is divided

q.

\

$

r

t

s,

t*

R,

t/

v

\

t

H

*

B

F

F

I

F

;

h

l

n

T

t

T

'l

If Free

Surface

Correction

data is

not

the following

formula

can

be used

.I:*9::ae-

r*e 1199 9r

-.

t

adss--e

t,.J

v

-


67/109


68/109

-67

5.32.I

For

Trimf,

Using

LCG(FP)

=

LCG(

FP)

of

Constant

=

'tT6--+..53.40

M

,l

F

T

t

$

s

F

F

;

;

;

I

t

.A

Vr,t^"'f,'

-tt

t)

S

.4

{

b

\

{

\N

F

i

lir

$

a

q

=

LCG(FP)

of

No. L

FOT=

=

Longitudinal-

Moments=

46.51 M

Weight x LCG(FP)

Isa

V

r2r-40

23794.40

Total

Moment

Tota1

Moments

TotaI-

wETgirts

1483410.

1-3 Total

Moments

22L29.60

T

67.03

M

ry:rc'

^r

ucB

I

New

LCG(

FP)

LCB(

FP)

trP

-l'

Trim

Lever

,"'

rrim

=

ry

Ot-.;2+

I'f

itufir

-

66.58

M

=

LCB(

rp

)

:

Sc-e

(f

v1

=

67.03

-

66-58

=

0.45

M

=

Trim Lever x

DISP

{l

MTC

0.45

x 22129.6

t c(

241'8

.^.,.\

ut"\*

v

=

41 Cm

ltlu

",

-

ao-\

\ts

s--

change

of

Draft

=

Trim

=

+

=

20.5

cm

or

0.205

LCG(FP)

is Aft of

LCB(FP),

therefor"

Sh;

is trimmed

"By

the

Stern"

NOTE: Draft,

MTC, LCB

and

DISP lvere

calculated

in Chapter

I

I

I

I

L2r.40

W.

/'

136

r:-)21.49

J*

tt't

'f

H

n(r,

fr

(,:

T\,rro,

Draft

and Deadweight

Surveys.


69/109


70/109

s

[

+

a

\A

F

I

\

tu

f-

b.

\iJ

t-

a_

-,69

-

j

'il

9sr

.n

=S

-:.S

-b

r

5:

iii

r.

rc5

t.

EE

E*

3;

oo

oFl ea

EE

::

i.;

.E

e

F.E

E.i

gq

rE

sA

g

Ei

E

E6

Eg

g

Cii c H

g.S

iH

;*

F5

tt

E

?E

T:

E

gE

FF

Egg

IE

gE

?F$

3;

FF

=HE

tEE

E*,gii

E;g

;gE

:sr

;:,

g

g

Rolllng

co.ttici.nt

t

(

-

I

t.05

t.00

l-t

t.o

0.9

l7

r6

t5

l4

r3

,T,

B .f

i,tg'ryl

-|

flr\

Er..npl.:

f

.

0.8;8.

GM;l

I

.

12

r.c

GM

.

0.38

m

itETRlc

tJwtT

-

s1a.

tt-:- r2

T

0.90

r

(

(-t

t.

Ercrdth

B

(ml

RollinO

prriod

T

(rccl

I

Figure

21


71/109

22,t32.8

r

6.7s9

|

14.r.60rJ3

|

7,77t.8

DECKHEICHTS

CCM

xi-r

-

rxr{

9220

No.2

--

fC

6'7t9

No.3

-

cM

31I-

No.t-

cfi'0365

No.5

_-

Gtyl.o65

No.6

-

ROLUNGPERIOD'J@_

sTAflsncs:

wr/Pc-

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rr/(Mr)

BM

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^CTU^L

DRAFT

DEPARTURE:

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yd-

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EB(FP)

66.,r5YF

lJ5

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IO^DTNG

?ORT:

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STA8ILITY

ANO

TRIM

CALCULATION

REPORT

DEPARTURE/ARRIV^L

LOADINC

DATE:

-

VOY.

NO.:

lO^DIl{C

QUA}{T TY:

-

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73/109

-72

LCG(FP)

METHOD

CHECK

LIST

t

5.33

The

fotlowing-list

summarizes

the

steps

to

calcu-

lateTrj-mandFwd/AftDraftsatthenextloading

or

discharge Port'

5.33.1

Check

Fwd

and

Aft

Drafts

upon

arrival

and

solve

for

corrected

trim'

5.33.2

Deduct

fuel

oil

and

water

consumed

from

DISP

at

previous

port

'

Add

ballast

water

if

taken

in;

subtract

if

discharged'

5.33.3

Using

DISP

calculated

j-n

5

'

33

'

2

'

refer

to

Hydrostatic

Tables

and

obtain

Draft

'

MTC

and

LCB.

Check

Sg

to

account

f.gr

any

difference

from

Mean

Draft

found

in

5'33'1'

5.33.4

Solve

for

Total

Longitudinal

Moments

on

arrival.

Work

back

from

Trim

to

Trim

Lever

to

LCG(FP)'

5.33.5 Measure the LcG(FP) of all weights to

be

loaded

or

discharged'

Solve

for

their

Longitudinal

Moments'

5.33.6

The

New

Total

Longitudinal

Moments

equals

5.33.4

Plus

or

minus

5'33'5'

5.33.7

Add

alI

weights

taken

in

and

subtract

all

weights

discharged

to

find

new

DISP'

Refer

to

Hydrostatic

Tables

for

new

Draft

'

MTC

and

LCB'

5.33.8

Solve

for

new

Trim

and

Fwd

and

Aft

Drafts'

-R

x-

q

+

M

F

*t

\rr

ft

R

{


74/109

GENERAL

CHAPTER

SIX

GRAIN

LOADING

6.1 If a ship i.s to darry grain, it

must have

a

Grain

.

Loading

Plan.

This

plan

must

meet with

IMco

and

SOLAS

reguirements,

and

must

be

approved

by

the

approPriate

Government

AgencY-

IMCO

ANd

SOLAS

REQUIREMENTS

6.2

The

IMCO

and

SOLAS

requlrements

for

loading

grain

are:

6.2.1 The Angle of Heel due to shift of grain

shall

not be

greater

than

twelve

(

\2')

degrees

'

6

-2.2

'

The

residual

stab

j-lity

area

shal-1

not

be

Iess

than

0.075

metre-radi-ans.

6.2.3

The

correct

metacentric

height

sha1l

not

be

less

than

0.30

metres.

GRAIN

STABILITY

CALCULATIONS

6.3

The

trim

and

stability and Grain stability

should

be

made

as

soon

as

details

of

the

grain cargo

to

be

l-oaded

are

received.

Depending

on

the

stowage

Factor(SF)ofthegraintobeloaded,slackholds

may

be

reguired.

check

the

approved

Graj-n

Loading

Ptand

for

the

designated

slack

hol-ds

in

this

situ-

6.4

ation.

The

actual-

Horizontal

Heeling

Moment

(

HHM)

is

equal

to

the

Volumetric

Heelj-ng

Moment

(vHM)

divided

by

the

Stowage

Factor

(SF)

of the

cargo'

Heeling

Moment

=

Volumetric

Horizontal

Mo{ten

'

Stowage

Factor

of

Cargo(rq3/r3)

q

\\/

\rr

-\

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$-

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77/109


78/109


79/109

-

78

CALCULATION

OF STABILITY

FOR

A

GRAIN

SHIP

LOADING

TO

THE

GRAIN

RULE

EOUIVALENTOF

r9@.

cARGo

PLAtr:

TNDT.ATE

Holos.

T. ocKs,

ENG.

R@M.

cAR@.

FEoERs.

TRUNKs,

sEcuRo

ANo

uNsEcuRED

GRAIN

SURFACES,

S'AT

AilY

XEMPTIO'{S

FROM

THE

1960

OUIVALEI{T:

I

CFTIFY

THAT

TH

CALCULATIONS

SHdVN

IN

THIS

DOCUMET{T

INDICAT

STASILITY

VALUES

WHICH

II'ILL

8E

IIIAINTAINEO

OR

THIS

VESSEL

THROUGHOUT

IH VOYAGE.

-

{

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&

$

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=

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NAME

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l'lUM8R

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raaL I.CALCULATION

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Documents

Draft Surveys