While drilling loaded as shown in Sample Load Form #4 (Drilling), the DEEP DRILLER suffers a sudden unexpected inclination to starboard and aft. Strong wind and high waves are on the port bow. Among the possible causes, you should consider __________.

Correct Answer: Option D — failure of mooring lines 1 or 2

Strong port bow environmental forces combined with a starboard-aft heel strongly implicate the failure of windward mooring lines 1 or 2. Loss of these lines allows the MODU to fall off station, inducing severe yaw and list.