Thanks for the info.
I got a quote for 219 euro for a 2 berth window cabin which is jut a bit expensive for two nights on a ferry and less than three hours in Cherbourg.
I can ago on BF return for 70 euro and have a full day in Rennes, and a crossing on the Pont Aven.
I would also have to pay 38 euro for a return Holyhead to Dublin fare, so not likely to go . Why can't IF market better. the ship is empty so surely a more reasonable offer to entice people would make sense.