A tanker with 22 sailors on board is drifting 100 miles west of Loop Head in Co Clare after losing power in its main engines.
The tanker is carrying 15,000 tonnes of caustic soda and is bound for Aughinish in the Shannon Estuary.
Sea conditions are said to be rough with a six-metre swell and winds of up to force eight. The ship is not, however, believed to be in danger.
The Irish Coast Guard is monitoring the ship. Its helicopter, based at Shannon, may be used tomorrow to ferry engineers and parts to the stricken ship. A tug may also be sent to assist.