You've probably read this before in how-to books, but it's true: the closer you get to your subject and the larger your main elments are in the frame, the more dynamic your compositions will be. There are two ways to get closer to your subject: one is to simply walk a few steps closer, the other is to use your zoom lens to fill up the frame. (In this case, of course, one more step and I would have walked off the dock and into the drink, so zooming was the better option.) One of the nice things about digital is that you can see your results instantly on the LCD and if you're not filling the frame, get closer.
The key thing is to try and elminate anything that doesn't help carry the theme of the shot. If someone has to ask what it was you were shooting, you've probably included too much distracting information. In composing this shot I was careful to exclude anything but the boats and one small corner of dock. The shot was pretty tight as it was taken, but I also cropped a tiny bit more during editing. Move close, fill the frame--you'll love the results.