It seems to be a Catamaran for people only, no vehicles.
Two return trips a day most days, 90 mins is quicker than the Steamship. £48.75 return is very reasonable.
I took a look and was struck by how much the service varies from one day to another - it seems to lack pattern and I wonder if that's tidal, what it does for regular traffic that might like consistency, or have I totally missed something? A sample month:
The white on yellow looks good on the pictures of the cat - I found it hard in their timetable and I have colour adjusted the screen captures here to make it (for me at least) more readable. Again, others may find the originals easier on the eye ... I appreciate I am reading / posting in the middle of the night.