I have found that the black gas line pipe(1" I think) at Home Depot or Lowes is just a scosh smaller than the yakima bars, and if you put them into Yakima towers, you can clamp the towers tight enough to secure them. This means you can get a 10' pipe, cut it in two, and have 2 60" cross bars for $20 instead of $70 if purchased form Yakima. Also, Home Depot will cut pipe for you (saved me from the hack saw), and they can even thread the shorter peices.
Right now, I just have a couple of bike trays mnounted to it, but I figure if I ever need to, I could cut my cross bars in half, and insert a T-Fitting, so I oculd put some vertical bars in like stackers to secure more boats. This is mostly in thought mode as I have not actually tried it yet.
"If I'm not there, it means I'm dead...or late!" General W.R. Monger