This website: The Cruel Sea by Nicholas Monsarrat shows that the jacket was designed by John O'Hara Cosgrave II (ie the 2nd)
I too have a copy belonging to my late father. I’ve read the book many times. I have very fond memories of watching the film with my Dad when I was growing up.I still cherish my late fathers copy, a gift to him in 1950 after serving his time on the Clyde and going to sea as an Engineering Cadet.