Yeah, I'm not sure. I mean, any idea can work with a dedicated group that's willing to contribute, but those players are sadly few and far between. I think the idea of having a ship is interesting, but I do think having some kind of driving force would be helpful too. If the raiding party returned from a raid (successful or otherwise) to find their village destroyed or something, it might compel them to go seek out and destroy the people responsible. Gives it a bit of a questy starting point.
Just an idea we could chew on. Also, trying to make all the interactions either traveling or fighting isn't the best idea, in my opinion. Too much fighting becomes just as monotonous as too little. My two cents, anyway.