The 300-gt Adler Express (built 1994) hit a quay in Wittdun on Wednesday at eight knots, injuring 27 people.
German accident investigators said the cause was a malfunctioning component in the steering control.
The vessel will now have its bow repaired in Husum over the next four or five days.
The two passengers who suffered life-threatening injuries have been taken out of intensive care.
