Though not advertised as a sequel, "Ship of the Damned" is pretty much a sequel to "Fragments" with some of the same characters and tech.
These, combined with the historic tale(??) of the Philadelphia experiment make for an enjoyable read and intrigueing story.
I was particularly pleased to meet Ralph again. He is one of my favorite characters of all time! Seldom does an author develope a character... especially a "special" character... so well. I almost feel he is a personal friend of mine.
This is a really good read with an interesting plot, good characters, solid writing, and plenty of action.