Don't think for a second that anchoring problems are solely the domain of small craft..
I spent six months on an old passenger ship (300-odd passengers) around Singapore/Malaysia out 10 years back and we got bumped in the nose by a container ship trying to anchor in front. The tide was running about 5knts, it was a pitch-black night and he drifted down onto us whilst trying to put his hook down.
Scared the crap out of a fair few of us (including me!) and resulted in a new bow for us (just cut off the old one and weld on a new one!). He was extremely lucky that we didn't sink him, since our curve bow of 1/2" plate penetrated his engine room up to the edge of the superstructure (about 3ft). I must post photos when I get them scanned in..