Thanks for the help pointing out more details on what I described very briefly. I composed that post on my phone - should have waited until I had a keyboard.
An overhand bight looks like this
http://en.wikipedia.org/wiki/File:Ov...-ABOK-1046.jpg
Good catch SAT on the bights in the photo, I had no idea they were visible in any of the images.
With the rope, you simply want a loop at each end and a bunch of loops along the length of it. The finished product should be about 20 - 22 feet long. The perimeter of a king mattress is 26 feet in total. You want the rope you make to be a few feet shorter because the first time you tension it, the knots will draw tighter and the rope will be 2 or 3 feet longer.
Also, remember to make the overhand bights at least 3 inches long, 4 would probably be better, because as the knots tighten up when you first tension it, the bights will become a little shorter.
The first time I made one I had to tie, untie, and retie several times before the length came out right. Mine is still a little longer than it should be, but I was tired of messing with it.
On the ratcheting cargo strap, get a good one, don't be tempted to save money on it. The cheap ones are hard to tighten down, harder to loosen up and often fail outright after a few uses.
I did not research or look for other bed restrain designs, as this one struck me as sufficiently simple, effective and inexpensive. The only limitation is that the rope ends up secured to the mattress, not the bed frame. So, the mattress can slide around, but that's never been an issue for me.
My first design was heavier, more complicated, more expensive but still, not nearly as useful. That design fastened to the bed frame or bed legs - but on most hotel beds, that was not easy to do. You can see that one in a few of the photos, it featured a 48" long, 1-1/2" dia. wooden dowel. The dowel was drilled through about every 4 or 5 inches to allow ropes to be tied to it. At both ends of the dowel were two cargo straps, that both went to one leg. It was overkill, only gave 48" of tie points on two ends of the bed, was hard to transport, and I was always banging my chins into the damn ratchets, or sitting on one - unpleasant while naked.
Bravo!!! 