Funny thing is, I had two rafted up powerboats drift into me just this past Sunday. This was in on Lake Michigan, too, where there are no tides or currents to worry about and only about 7kts of wind at the time.
Of course, we were in an area known as "The Playpen" since it's the main anchorage in downtown, just north of Navy Pier. Most irritating part of it all is that I deliberately picked a spot where I could give myself adequate scope and they anchored pretty much on top of my rode with the 1.1:1 scope that's apparently standard anchoring procedure for power boats.
No damage, fortunately. Still, it was irritating because my wife kept asking me if I was sure that it wasn't something that I had done, even after I explained that we couldn't have drifted upwind into them.
And this thread was growing faster than I could read it for about four pages. It's probably up to page 14 by now.
1972 C&C 35' Mk I
Belmont Harbor, Chicago, IL