After 24 hours of being stuck, a second attempt to refloat the Aratere near Picton, was successful last night.
The government says it is disappointed in Kiwirail - and has criticised the way it maintains the ferries.
The Transport Accident Investigation Commission is now involved, along with Maritime NZ and Kiwirail itself.
Investigation Commission spokesperson Simon Pleasants says three people will be appointed to look at what happened.
