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Vessel Stabilit

y

BOS-

P

RD-2

6

.900

6

01

4

.1.

7

Stabilit

y

s

o

f

twa

r

e l

o

a

d

i

ng

cond

iti

on

test.

T

he

p

ur

p

ose

i

s

to ensure

the o

p

erat

i

ona

l

accuracy of

the

stab

ili

ty

soft

w

are

and

test

records

are ma

i

nta

i

ned

.

D

ur

i

n

g

the

l

oad

i

n

g

test

,

one

of

the

sh

i

p

's

Se

n

i

or

Off

i

c

e

r

s

i

s

to

o

p

erate

the

l

oad

i

n

g

i

nstrument

and

ca

l

cu

l

ate

the

test

cond

i

t

i

ons

.

T

he

resu

l

ts

obta

i

ned

from

the

l

oad

i

n

g

soft

w

are are

to

be

i

dent

i

ca

l

to

those

stated

i

n

the

stab

ili

ty boo

kl

et

.

T

h

i

s

test

shall

be

p

erfomed at

l

east annua

ll

y

.

4

.1.

8

F

r

ee s

u

r

f

a

c

e e

ff

e

c

t

I

f

a

tan

k i

s

com

p

l

ete

l

y

f

ill

ed

w

i

th

liq

u

i

d

,

no movement

i

s

p

oss

i

b

l

e

and

stab

ili

ty

i

s

p

rec

i

se

l

y

the

same

as

i

f

the

tan

k

conta

i

ned

so

li

d mater

i

a

l. W

hen

a

q

uant

i

ty

of

liq

u

i

d

i

s

w

i

thdra

w

n

from

the

tan

k

the

s

i

tuat

i

on

chan

g

es

and

the

stab

ili

ty of

the

sh

i

p

i

s

adverse

l

y affected by

w

hat

i

s

k

no

w

n as

the

free

surface effect

.

T

he

adverse

effect

on

the

stab

ili

ty

i

s referred

to

as

a

l

oss

i

n

metacentr

i

c

he

i

g

ht

(G

M

)

or

a

v

i

rtua

l

r

i

se

i

n

Vert

i

ca

l

Centre of

G

rav

i

ty

(

VC

G).

T

he

free

surface effects

of a

ll

s

l

ac

k

tan

k

s

shall

be

ta

k

en

i

nto account

i

n any

ca

l

cu

l

at

i

ons

.

W

hen

i

t

i

s

i

ntended

to

i

ntroduce

or

d

i

schar

g

e

ba

ll

ast

w

ater

dur

i

n

g

a

voya

g

e

the

Maste

r

shall

p

r

i

or

to

de

p

arture ensure

that

the

re

q

u

i

red

stab

ili

ty

cr

i

ter

i

a

i

s ma

i

nta

i

ned at

a

ll

t

i

mes

due

to

l

oss

of

stab

ili

ty by

p

art

i

a

ll

y

f

ill

ed

tan

k

s

.

T

he

free

surface

shall

be

k

e

p

t

to

a m

i

n

i

mum

; i

f

p

oss

i

b

l

e

on

l

y

one

tan

k

of

each

ki

nd

of

liq

u

i

d

shall

have

a

free

surface

. T

he m

i

n

i

mum

G

M

shall

be ma

i

nta

i

ned

as

s

p

ec

i

f

i

ed

i

n

the

Stability Booklet

.

W

hen

a

tan

k i

s

to

be

ba

ll

asted

at

sea

,

to

counteract

the

l

oss

of

consumab

l

es

i

t

shall

be

noted

that

the

tan

k

s

have

a

com

p

l

ete

free

surface

as

soon

as

ba

ll

ast

i

n

g

commences

and

the

free

surface

shall

adverse

l

y

affect

the

stab

ili

ty of

the

vesse

l

before any benef

i

t

can

be

assumed

from

the

w

e

i

g

ht

of

ba

ll

ast

w

ater

ta

k

en on

board

F

ree

surface

va

l

ues

for

d

i

fferent

l

eve

l

s

can be

found

i

n

the

tan

k

s

ca

p

ac

i

ty

tab

l

es

.

4

.1.

9

F

r

ee s

u

r

f

a

c

e i

n

te

r

a

c

ti

on

s

on

stabilit

y

T

he ma

xi

mum

free

surface moment

of

each

tan

k

shall

be

used

w

hen

they

are

not

fu

ll (

p

ressed

-

u

p

),

or

are

not

em

p

ty

(

str

i

pp

ed

dry

),

throu

g

hout

a

g

i

ven

voya

g

e

. T

he

i

nf

l

uence

of

tr

i

m

i

s

usua

ll

y

no

t

ta

k

en

i

nto

account

w

hen

hand

ca

l

cu

l

at

i

n

g

the

free

surface moments

.

M

anua

l

ca

l

cu

l

at

i

ons

are conservat

i

ve

because ma

xi

mum

free

surface

correct

i

on

i

s

used

,

w

hereas

soft

w

are

ca

l

cu

l

ates

rea

l

free

surface effect

.

4

.1.1

0

Gu

a

rd

i

ng

a

g

ai

n

st a

nd pr

e

v

e

n

ti

ng

f

r

ee s

u

r

f

a

c

e e

ff

e

c

t

T

o

g

uard

a

g

a

i

nst

and

p

revent

free

surface

effect

the

number

of

p

art

i

a

ll

y

f

ill

ed

tan

k

s

shall

be

k

e

p

t

to

a

m

i

n

i

mum

. T

an

k

s

that

are

e

i

ther

com

p

l

ete

l

y

fu

ll

or

com

p

l

ete

l

y

em

p

ty

do

not

have

a

free

surface

effect

and

therefore do

not

reduce

the

vesse

l’

s metacentr

i

c

he

i

g

ht

(G

M

).

A

nt

i-

ro

lli

n

g

tan

k

s

have

a

free

surface

effect

,

w

h

i

ch decreases

the

vesse

l’

s

metacentr

i

c

he

i

g

ht

(G

M

). T

hey

should

,

therefore

,

a

l

w

ays

be em

p

t

i

ed

w

hen

the metacentr

i

c

he

i

g

ht

i

s

sma

ll.

F

ree

surface

effects

are

not

on

l

y

caused

by

p

art

i

a

ll

y

-

f

ill

ed

tan

k

s

. T

hey

can

,

for

e

x

am

p

l

e

,

a

l

so

be

caused

by

accumu

l

ated

w

ater

on

dec

k. T

o

enab

l

e the

w

ater

to

run

off

q

u

i

c

kl

y

,

a

vesse

l

shall

have

ade

q

uate

free

i

n

g

p

orts

. W

ater

shall

f

l

o

w

eas

il

y

to

the

free

i

n

g

p

orts

w

h

i

ch

shall

a

l

w

ays

be

c

l

ear

.

W

hen

l

oad

i

n

g

dec

k

car

g

oes

,

care

shall

be

ta

k

en

to

avo

i

d

any

obstruct

i

on

of

the

free

i

n

g

p

orts

or

areas

necessary

for

the

dra

i

na

g

e

of

p

i

p

e

sto

w

a

g

e

p

os

i

t

i

ons

.

Vers

i

on

SF(BOS-

P

RD-0

7

.900

6

01-

ver

.0

4

). O

r

i

g

i

na

l

date

: 22/0

6

/2012.

Vers

i

on

date

:

3

1/12/201

5

.

Va

li

d

vers

i

on

on

l

y

on Q

M

S

s

i

te

.

Uncontro

ll

ed

document

w

hen

p

r

i

nted

.

P

rocedure

p

re

p

ared by

: BOS

Head

of

O

p

erat

i

ons

.

App

roved

by

: BOS

Head

of

O

p

erat

i

ons

.

Va

li

dated by

: BOS

Qua

li

ty

R

e

p

resentat

i

ve

.

7

/ 1

3

341