One of the things that makes me think that the author of Das Boot is a good writer is his ability to accurately describe an environment where nothing in happening.
That is not easy to do in writing. I hope you enjoy both books.
Neither was intended to be a technical or historical academic work. They were intended as memoirs recording human experiences. Both of these books did a good job in capturing the human aspects.
About once a year, I re-read Iron Coffins and I enjoy the read every time.