Capalonga
Was it not an ex Hull ferry?
No not a Ferry in now a days format (roll on roll off)
Built 1958 as a rather standard freighter as MV Bolton Abbey but indeed on a Ferry route Hull - Rotterdam so probably with extra passender capacity.
Transferred into diving vessel Capalonga in 1972 for the Adriatic. Extensively modified into Dynamic Positioned
Deep Sea diving vessel in 1977 in Amsterdam.
Scrapped 1983.
Cheers SLB