Alteration of course in heavy weather

	Dangerous/critical period when sea comes from beam.
	Wave group consists of about 8 waves.
	Lull period 1-2 waves  among wave groups.
	Alter the vessel during lull period.
	Before turning, inform all department heads, take necessary precautions.
	No one is allowed on deck.
	Understand turning ability of the ship.
	Study wave development cycle carefully to find out calm period.
	To minimize danger of being capsized or swamped, the timing of turn to be coincide with calmer waves when abeam.
	Consider possibility of misjudgment of lull period and turning ability of the vessel.
	About 2/3 waves before the calm wave, start turning slowly with extreme caution.
	If turning misjudged, come back to previous heading.
	If turning is correct, continue the turn as fast as possible.
	When critical period is passed, increase the turning rate.
	Steady to next course and observe situation carefully.
	Adjust speed if necessary for following and quartering sea.