Using the V2 Directions Profile with the Way Category option a ferry route returns the Way Category as a 8 instead of a 4.
Here are the coordinates of the ferry route:
Select the option extra_info: waycategory. The return value is an 8 rather than a 4.
Just pinging to see if there is any activity for this issue.
I just saw this post from a while back that states the documentation is out of date.
A Way Category of 8 is now the ferry category.