BALLASTING, DEBALLASTING, BUNKERING AND CONSUMPTION OF FUEL AND TAKING AND CONSUMING OF WATER ARE ALL PART OF DAILY WORK ON SHIP. DUE TO THIS THE QUANTITY OF FLUID INSIDE THE TANKS CHANGES. NOW IF THE TANKS ARE FULLY FILLED WITH FLUIDS THEN LIQUID CANNOT MOVE WITHIN THE TANK WHEN SHIP HEELS AND THE LIQUID ACT AS A STATIC WEIGHT WITH ITS CENTRE OF GRAVITY AT THE CENTRE OF GRAVITY OF THE LIQUID WITHIN THE TANK. HENCE THE CENTRE OF GRAVITY OF THE SHIP WILL REMAIN AT SAME POSITION I.E AT G.
BUT IF THE TANK IS NOT FULLY FILLED AND THE SHIP HEELS THEN THE LIQUID WILL MOVE IN THE DIRECTION OF THE HEEL. THIS LEAD TO THE SHIFT OF THE CENTRE OF GRAVITY FROM “g”OF THE FLUID TOWARDS THE DIRECTION OF HEEL TO” g1″.
AS A RESULT THE OVERALL CENTRE OF GRAVITY OF THE SHIP MOVES TOWARDS THE DIRECTION OF HEEL FROM G TON G1 PARALLEL TO gg1. IF WE MAKE A VERTICAL LINE TO CUT LINE GM THEN IT CUTS AT G(F) . HENCE THERE IS A NEW GM I.E G(F)M. HENCE THERE IS A VIRTUAL LOSS IN METACENTRIC HEIGHT LEADING TO LOSS OF STABILITY.
