A remarkable case of capsizing of a small trawler

15 y Sc!ipsbuwimde

ARCH ¡EF

_{Technche Hogeschoo}

water in the

Body Plan seo fig. 1.

aft store abt

1.25 ni

engine room abt 0h20 ra above the ciliad.er heads

fishhold abt 0.60 ni above the concretion on th bbtoai crows quarter abt 0.75 ni above the floor

no water in the foropoak

all tanks on port full with seawater on starboard nuch fewer soawat r

Length over all , (_f_

- LJ'_)

Length at design drught 19,00

Breadth

5.60

D dp t h

2.85

Moan Draught above keol 2.00

Draught fwd dsigii

_1.85

Draught aft

2.15

At the momnt of oepsizing - Driught fwd

1.93

nf t

2.56

Displacement (mol. sholiplating)

in soawtor

98.73

Contro of Gr :vity above keel 1.93 abaft half of the length

0.32

GM

0.94

Again in the upright positions

A RKABLE CAS: 0F CAPSIZING 0F A SMALL TRÁ7LIR

Deift

J G. DE 11T

INTR0DUCTI0I'

During a heavy gale a small Dutch -brawler capsized and remained floating upside doam for «bout 20 minutes. Thon the vessel began to heel

again slowly and suddenly returned into its normal position. Being back in the upright position thora wore big quantities of water in the hold, tanks, quarters and angine room. The upper part of the steering bridge-house was torn off. Ono member of the crow of 5 was lost. In this upright

position again the ship was very unstable and the crow was able to improve the behaviour and the stability by paying out 50 fathoms of the warp at the end of which a ballast vioight of 50 kg vías comiectod and by discharging water with buckets and a handpump. The weather improved and the vessel was towed into harbour safely.

In connoction with the investigation by the Navigation Board the stability of this ship was studied by Ir, L.F. Hurfot of the Tochnicl University at Dulf-t. Due -be tuo fact that the vessel and rt of the crow wore rescued it was possible to reconstruct the loading condition at the moments of e .psizing and regaining the upright pocition again rathor accurately.

-2-S e a conditi on

According to meteorological data the aind and se:coidi-tions were

direction of the vzind

330°.

7indforce according ta 10 of the Beaufort Sca1evelooi-ty

85

_{- 95}

lan/hr vii-th guts 0±' -- to 1 minute possibly :bt 120 km/hr

vii-th intervals of some minutes

ave height 4 - 5 m

individ.ual viaves 50% higher probably one

each 30 minutes.

Rîave length 80 - 100 ni.

General picture

confused sea.

P1ace

8 naut. miles east o

ST.3 - buoy

(53°-32.5 NL

-

4°-2'EL)

Dateg 7th Octobre 1954.

Stability Calcul-tian.

Fello;sT method forthe calculation of the cross-curves of the

statical stability was usad and a body plan according to Tschebyscheff

scalo 1

20. The cross-curves viere do±ermiiod for heeling anglos to

180°.

Curve 1 of fig. 2 is the curvo o rightiiig lovers for the condition

in which tho vassoi capsized, At 35

the dynamical stability vins 153 mm

For the calculation of this condition the su2orstructuro was not taken

into account. Duo to th

damage discovered afterwards the superstructure

must have boon flooded very soon.

In the upside down position the vessel has sufficient stability to

prevent the vessel to rcturn to her upright position. Thorofore the

ves-sel will romain floating in this position for a considorablo time. In

the moantinio seawater will ponotrato into the vassal through hatchos,

vontilatorpipos and into the tanks through air vont pipos.

The disp1acmont will incroaso. Curvo 2 of fig. 2 represents a

dis-placement of abt 156 ton. TIne stability is unsuffician-t in this

condi-tion, Duo to froc-surfaces of the viator in the vessel, the stability

doeronsos still furthor and. is rnproducod in curvo 4. For this

condi-tion the quantities of water ponotratod into the vessel v;oro nearly

eccording to tho estimates made by the crow after returning to the

upright position. As mentioned already the port oil-fuel tank 'iias much

moro flooded than the starboard tank. Due to this

unsymmetrical

floo-o

ding the ship vail Ithoolt froni 180

to 130

and will romain rolling at

about this point of cquilibrium. From the curvo 4 it can be soon that

the area betvîeon 76

and l30

is vary small now. It needs only the wor

exercised by a heavy wave to push the vassoi to a position of abt. 10

If the flooding should not have boon unsymmetrical the curvo of

righting lavors should have boon according to curva 3. It can ba

doub-ted whethor the vass1 vîould hava regained the nearly upright position

again.

Conclusions.

The stability of this vassoI cama up to the Rahola at ndrd. fully.

Capsizing must 'D

owed to the aburma1 forcas caused 'ay a very

heavy ground-sea.

Horfs-t

Ir

L.P.

Vorsiag van hot ondorzock naar do

stabili-1955

toit van do viskottor OX. 60

(Report of the investIgation into the

sta-bility of the fishingvossal TJ}C,60)(Unpublishod)

E 4o n

co

i 2o

/

r?

CURVE

INTACT STABL1TY - Dt5PLAOEMEt-T

98.73 m3

CL)QVE 2

PARTLY

FLOODED-A& 156

SURFACES.

C.L)RVE 3

PAR.TL'1 FLOODED - DI5PL. ABT.

56 r

FREE 3uRFACE

EDuCTlor NCLUDE

NO PENETRATION OF

t'i PoRTSD

OF.Î

CURVE 4: A5 CURVE 3. PORT5 IDE

FLootE.D AS OB5ERVEr'

FIG.2

5:

4o

_{OIL FUEL TAr1i}

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