SYNCHRONOUS ROLLING IS CAUSED BY THE SHIP’S ROLLING PERIOD T(r) BECOMING SYNCHRONOUS OR RESONANT WITH THE WAVE PERIOD. WHEN THIS OCCUR, THE SHIP WILL HEEL OVER AND , IN EXCEPTIONAL CIRCUMSTANCES, BE ROOLED FURTHER OVER BY THE ACTION OF THE WAVE.
CONSEQUENTLY, THERE IS A SERIOUS DANGER THAT THE VESSEL WILL HEEL BEYOND A POINT OR THE ANGLE OF HEEL FROM WHICH IT CANNOT RETURN TO AN UPRIGHT CONDITION. THE SHIP ENDS UP HAVING NEGETIVE STABILITY, AND WILL CAPSIZE.
TO REDUCE SYNCHRONOUS ROLLING :
- USE WATER BALLAST CHANGES TO ALTER THE KG OF THE VESSEL. THIS SHOULD ALTER THE GM(transverse) AND HENCE THE NATURAL ROLLING PERIOD T(r) TO A NON-SYNCHRONOUS VALUE.
- CHANGE THE COURSE HEADING OF THE SHIP SO THAT THERE WILL BE A CHANGE IN THE APPROACHING WAVE FREQUENCIES.
- ALTER THE SHIP’S SPEED UNTIL SYNCHRONISM OR RESONANCE NO LONGER EXISTS WITH THE WAVE FREQUENCY.
