"C" Class vessels

I am working on a data base of ships that were docked down in Rosyth Dockyard from 1916.

I have already made up a word Doc that I gave to a colleague of the ships that docked down from 1916, but now are trying to Define the types of those ships.

Can anyone shed light on the foillowing "C" class vessels

C 30
C 119
C 611
C 714
C 711
C 712
C 713
C 714

Your help would be very much appreciated