A wave height within the vessel’s operational limits of 2.7 metres (8.9 ft) in the Irish sea had been forecast but the conditions were “significantly rougher,” the operator said.
Another passenger said they had “never experienced such a rough crossing and there were a lot of very frightened people”.
“The staff deserve a massive shout out,” they added.
The ferry did not reach its destination until 02:00 GMT – about four hours later than planned, according to one passenger.
Steam Packet said it was in contact with passengers who had been affected but could not provide details on individual cases.
One of the vessel’s engines was shut down during the crossing after “an indication of smoke was detected” from that engine, it said.
The affected engine was shut down to allow for further assessment which was another “factor” for the delay to the service, the firm said.
Steam Packet thanked passengers for their “understanding and cooperation” during the sailing, adding “passenger safety remains our top priority”.
