Saturday, September 23, 2017
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How to Do Incling Experiment Onboard ship

THIS IS AN EXPERIMENT CARRIED OUT ON A NEWLY BUILT VESSEL ON  WHICH HAS A UNDERGONE MAJOR STUCTURAL CHANGES TO ASCERTAIN THE LIGHT KG OF THE VESSEL .

ONCE THE LIGHT KG IS KNOWN ,THE KG OF THE VESSEL CAN BE FOUND OUT IN ANY CONDITION

SOLAS REQUIRMENT

EVERY PASSANGER SHIP OR EVERY CARGO SHIP OF LENGTH >24M SHALL HAVE ITS LIGHT KG ASCERTAINED BY AN INCLINING EXPERIMENT.SUCH AN EXPERIMENT SHALL BE CONDUCTED WHEN THE SHIP IS FULLY CONSTRUCTED OR AS FAR AS FULLY CONSTRUCTED
EVERY 5 YEARS A LIGHT SHIP SURVEY SHALL BE CARRIED OUT ON A PASSENGER SHIP .IF THE DIFFERENCE IS MORE THAN 2% OR IF THE LCG OF THE VESSEL HAS BEEN DEVIATED BY MORE THAN 1 % THEN THE INCLINING EXPERIMENT TEST SHALL BE CONDUCTED AGAIN .

PRINCIPLE OF INCLINING TEST

WHEN A KNOWN WIGHT IS SHIFTED FROM ONE PLACE TO ANOTHER ,PERPENDICULER TO THE SHIP’S CENTERLINE ,THE VESSLE HEELS AND THE RIGHTING MOMENT ADJUST ITSELF TO EQUAL THE HEELING MOMENT .THE ANGLE OF HEEL IS MEASURED ,THIS PROCESS IS REAPETED AT SEVERAL ANGLES IN BOTH DIRECTIONS AND VESSEL KG  IS CALCULATED .

PROCEDURE:

A PLUMB BOB IS ATTACHED INSIDE THE CARGO HOLDS.
TO HAVE BETTER ACCURACY THREE SUCH BOBS ARE ARRANGED ,1 IN THE FWD, 1 IN MIDSHIP AND 1 IN THE AFT OF THE SHIP.
FOUR EQUAL WEIGHTS W1, W2, W3, W4 ARE PLACED ON THE DECK.
W1 IS SHIFTED ALONG WITH W3 AND DEVIATION IS OBTAINED .
W2 IS SHIFTED ALONG WITH W 4 AND DEVIATION IS OBTAINED .
W1 IS SHIFTED BACK TO ITS ORIGNAL POSTION AND A DEVIATION IS OBTAINED
W 2 IS SHIFTED BACK TO ITS ORIGNAL POSITION AND DEVIATION IS OBTAINED .
W3 IS SHIFTED ALONG WITH W1 AND DEVIATION IS OBTAINED .
W4 IS SHIFTED ALONG WITH W2 AND DEVIATION IS OBTAINED .
W 3 IS SHIFTED BACK TO ITS ORIGNAL POSITION AND DEVIATION IS OBTAINED.
W 4 IS SHIFTED BACK TO ITS ORIGNAL POSITION AND DEVIATION IS OBTAINED.
A MEAN OF ALL THESE DEVIATION IS OBTAINED AND APPLIED IN THE FORMULA
A VALUE OF GM IS OBTAINED FROM THE FORMULA .
A VALUE OF KM IS OBTAINED FROM THE HYDROSTATIC
A VALUE OF KG IS OBTAINED THIS KG IS ALSO CONTAINS THE WEIGHT OF THE WEIGHT USED e. THE KG IS FOR W+4w.
USING THE MOMENTS METHOD A LIGHT SHIP KG IS CALCULTED .

PRECAUTION TO BE TAKEN :

THIS EXPERIMENT MUST BE CONDUCTED ONLY AFTER THE VESSEL IS IN COMPLETION STATE OF THE CONSTRUCTION OR AS NEARLY AS POSSIBLE TO HER FINAL STATE OF CONSTRUCTION.
VESSEL SHOULD BE IN A SHELTERD ENVIRONMENT FLOATING FREELY AND AWAY FROM THE INFLUENCE OF WIND ,CURRENT,TIDE,PROPELLER WASHES OF OTHER VESSEL ETC.
VESSEL MUST BE IN UPRIGHT CONDITION ,HOWEVER IF SHE IS LISTED THE LIST SHOULD NOT BE GREATER THAN HALF DEGREE.
THE VESSEL SHOULD HAVE AND UNDULY LARGE TRIM BEACAUSE IF THE TRIM IS VERY LARGE THE HYDROSTATIC PERTICULARS OBATINED FROM THE PERTICULARS WOULD HAVE SOME ERROR THEREFORE A DETAILED CALCULATION OF THESESHOULD BE DONE BY THE NAVAL ARCHITECTS BEFORE CONDUCTING THE EXPERIMENTS
ACCURATE SIX SIDED DRAFT OF THE VESSEL MUST BE OBTAINED AND THE DENSITY OF THE WATER DETERMINED CAREFULLY.
THE VESSEL SHOULD BE SO FAR AS POSSIBLE IN HER LIGHT CONDITION WIT MINIMUM EXTERNAL WEIGHT ON BOARD,WEIGHT OF MORE THAN 4%OF THE LIGHTSHIP SHOULD NOT BE USED .
SHORE GANGWAY MUST BE REMOVED AND THE VESSEL BREATED OF THE JETTY FOR FREE.
THERE SHOULD BE ENOUGH UKC TO PREVENT THE VESSEL FROM TOUCHING THE BOTTOM DURING THE EXPERIMENT.
THE TOTAL SUM OF WEIGHT USED FOR THE EXPERIMENT SHOULD BE ATLEAST 1/500TH OF THE LIGHTSHIP WEIGHT.
EACH DEFLECTION OF THE PENDULAM SHOULD BE ATLEAST 15 CMS.
THE LIST PRODUCE DURING THE EXPERIMENT SHOULD BE LESS THAN 1° AND SHOULD NOT BE MORE THAN 4°.IF THE LIST IS EXCESSIVE IT WILL NOT BE PROMOTIONAL TO THE HEELING MOMENT PROVIDED.
THE LENGTH OF THE PLUMBLINE SHOULD BE BETWEEN 4-6 CMS.
FOR V/Ls WITH VERY LARGE GM MORE LENGTH OF PLUMBLINE OR MORE INCILNATION WEIGHTS CAN BE USES WHICH ARE COMPARITIVELY HEAVIER ,IN ORDER TO PRODUCE EFFECTIVE LIST.
IN THE ABSENCE OF INCLINATION WEIGHTS ,THE EXPERIMENT CAN BE CONDUCTEDUSING CONTROLLED WATER BALLAST BUT ONLY AFTER APPROVAL FROM THE ADMINISTRATION .
THE PERSON NOT REQUIRED FOR THE EXPERIMENT SHOULD LEAVE THE VESSEL AND THE PERSONS ONBOARD SHOULD POSITION THEMSELVE ALONG THE CENTERLINE.
VESSEL SHOULD BE IN HER SEAGOING CONDITION AND ITEM LIABLE TO SHIFT MUST BE SECURED IN THEIR POSITION SOME SHIPYARDS USE AN INSTRUMENT KNOWN AS THE STABILOGRAPH WHICH RECORDS THE LIST PRODUCED WITH REFERANCE TO THE TIME.

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