Stability of ships

⚡STABILITY OF SHIPS
SOFTWARES USED: 1.AUTODESK AUTOCAD 2014
2:FREESHIP V3.4
3:MODELMAKER
4:DEADWEIGHT(GF VIEWER)
5:MICROSOFT EXCEL
6:AUTOHYDRO
BY:
VIPIN DEVARAJ
DEPT OF SHIP TECHNOLOGY,
TRAINEE,INTERNATIONAL SHIPPING
BUREAU, KAKKANAD ,KOCHI
© VIPIN DEVARAJ, DEPARTMENT OF SHIP TECHNOLOGY,CUSAT

⚡ STEPS INVOLVED
• THE FOLLOWING ARE THE WORKS DONE:
1. INCLINING EXPERIMENT
• THIS EXPERIMENT WAS DONE TO FIND:
1.1 LIGHTSHIP VCG
1.2 LIGHTSHIP WEIGHT
1.3 GM
2. CHECKING THE REQUIRED STABILITY CRITERIA:
• THIS IS DONE USING RUN COMMANDS IN AUTOHYDRO EDITOR
• IMO AND KVI CRITERIA WERE CHECKED FOR DIFFERENT VESSELS
3. STABILITY OF VESSELS AT DIFFERENT LOADING CONDITIONS WERE CHECKED
• THIS WAS DONE WAS MODELLING THE TANKS AND WEIGHTS IN MODELMAKER
AND USING RUM COMMANDS IN AUTOHYDRO THE TANKS WER LOADED AND
THEIR STABILITY WAS CHECKED AT DIFFERENT CONDITIONS LIKE:
3.1LIGHTSHIP
3.2FULLY LOADED DEPARTURE
3.3FULLY LOADED ARRIVAL(TANKS <10%)

⚡ INCLINING EXPERIMENT
• AN EXCEL SHEET MADE FOR INCLINING EXPERIMENT WAS USED AND THE
FOLLOWING ARE THE INPUTS
1. MAIN PARTICULARS OF THE SHIP ARE ENTERED.
2. POSITIONS,WEIGHTS,VCG,LCG OF THE RESPECTIVE WEIGHTS ARE ENTERED.
3. PENDULUM DETAILS AND DRAFT READINGS TAKEN DURING THE EXPERIMENT ARE ENTERED.
4. USING AUTOHYDRO THE HYDROSTATICS ARE GENERATED AND THE DISPLACEMENT,LCB,KM AT
MEAN DRAFT ARE ENTERED.
5. DETAILS OF THE WEIGHTS TO BE ADDED AND REMOVED ARE ENTERED.
6. FREEBOARD READINGS ARE ALSO TAKEN TO CHECK IF THE VESSEL HAS THE REQUIRED
MINIMUM FREEBOARD.
7. DEFLECTIONS OF THE PENDULUMS ARE ENTERED AND THE AVERAGE GM IS FOUND AND VCG IS
FOUND FROM THAT USING THE FORMULA: KG=KM-GM

⚡ INCLINING EXPERIMENT

⚡ STABILITY CRITERIA
• IMO/KVI STABILITY CRITERIA WAS CHECKED FOR VESSELS USING AUTOHYDRO.THE STEPS
INVOLVED ARE:
1. THE BARE HULL MODEL(GF FILE) OF THE DESIRED VESSEL WITH TANKS OF SPECIFIC LIQUIDS ARE IMPORTED TO
AUTOHYDRO.
2. USING THE RUN COMMANDS IN AUTOHYDRO EDITOR,THE TANKS AND WEIGHTS ARE LOADED.
3. THE STABILITY CRITIRIA ARE CHECKED FOR VARIOUS LOADING CONDITIONS

⚡ STABILITY CRITERIA
• AFTER THE COMMANDS ARE RUN,THE CRETERIA IS CHECKED AND RIGHTING ARM VS HEEL
ANGLE CURVE IS GENERATED.

⚡ PASSENGER CROWDING AND TURNING HEEL
• IF THE BASIC CRITERIA IS NOT PASSED THERE IS AN ALTERNATE CRITERIA WHICH CAN BE USED TO FIND
THE STABILITY OF THE SHIP
• IF THE ACTUAL AREA UNDER THE CURVE UPTO THE ANGLE AT MAXIMUM RIGHTING ARM IS GREATER THAN ,
0.055 + 0.001*(30-ANGLE)
• PASSENGER CROWDING AND TURNING ANGLE ARE ALSO MEASURED FOR STABILITY

⚡ PASSENGER CROWDING AND TURNING HEEL
• THE REQUIRED DETAILS FOR PASSENGER CROWDING AND TURNING MOMENT ARE
OBTAINED FROM THE GZ CURVES AFTER PLOTING THEM .AND THE VALUES
• THE HEEL ANGLE CORRESPONDING TO THE PASSENGER CROWDING LEVER IF FOUND
FROM THIS GZ CURVE.
• IF THE HEEL ANGLE DUE TO PASSENGER CROWDING IS LESS THAN 10 DEG,THEN THE
VESSEL HAS PASSED THE CROWDING CRITERIA ALSO.
• SIMILARLY THE TURNING LEVER IS FOUND AND ITS CORRESPONDING HEEL ANGLE IS
FOUND FROM THE GZ CURVE.
• IF THE HELL ANGLE CORRESPONDING TO THE TURNING LEVER IS LESS THAN 10
DEG,THEN THE VESSEL PASSES.

⚡ STABILITY OF A MODELLED HULL
• A MODEL OF A VESSEL WAS MODELLED USING ITS DRAWINGS AND THE TANKS WERE
ADDED TO IT ACCORDING TO ITS GENERAL ARRANGEMENT DRAWING.
• ITS INCLINING EXPERIMENT CALCULATIONS WERE DONE

• ITS HYDROSTATICS WERE FOUND USING AUTOHYDRO AND ITS DIFFERENT LOADING
CONDITIONS WERE CHECKED USING IMO STABILITY CRETERIA IN AUTOHYDRO.
• 3 TIERS OF CONTAINERS WERE ADDED AND STABILITY CRITERIA WITH THESE
CONTAINERS WERE ALSO FOUND USING AUTOHYDRO COMMANDS

• COMMANDS USED TO CHECK THE STABILITY CRITERA AT
DIFFERENT LOADING CONDITIONS

⚡
THANK YOU

Stability of ships

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