Rhino,
Why on earth would they take the aircraft to a ship if not to carry out trials underway? Don't forget a ship underway is a ship not alongside or at anchor. It would be a complete waste of money to go there to sit at anchor - and at anchor the ship would "swing" which would make the situation even worse. Without actually having been there I can pretty well guarantee the the ship was moving (forwards) when the aircraft was operating to/from it.