Offhsore Structural Engineering by Dawson is another good one. No, it's a GREAT one. Wave loads can and are difficult to understand, though they really shouldn't be. they sure are, though, if all you have is Dean and Darlrymple's book and not enough experience with boundary value problems. It's just as bad with the USACE Shore Protection Manual. Why couldn't those books come with a lot of solved problems? Is that such a bad thing? Or at least come with a warning label on them...? Or why not charge double and include a bunch of solved problems?
Anyway, Dawson's book is written for engineering students and engineers who want to build things, rather than spend years tuning wave tanks just to learn what happens to individual sand grains over hundreds of years...