I once read this story or novelette, I don't think it was a complete novel but rather part of an anthology. There were lots of ships from all different times abducted into the far future. Among them a viking ship, a nuclear submarine from our age and some spaceships.

In this future the world is mostly water, the continents only exist as a kind of big gray quicksand. (when I saw Waterworld for the first time it actually brought this story to my mind)

It turns out that one of the ships only poses as a victim but actually is the one that dragged all the others out of their own time. But I forgot the reason why they did this.

The problem: I don't remember the author or the title of this story.
Who does?

Well I found the answer myself. Went to a small sci-fi convention and talking to some people we concluded this must either be a Poul Anderson or an A.E. van Vogt story. And then I found www.scifan.com (http://www.scifan.com) which is a very useful site. They have a chronological list of about 3000 topics that handle time travel: http://www.scifan.com/themes/themes.asp?TH_themeid=4&Items=
That gave me the answer.
The book was "The winged man" by A.E. van Vogt.
I reread it in the meantime, and found that I misremembered the viking ship, and also the reason why they were pulled into the future :)