Crab
I agree that the hi-line technique is a good way of getting someone off a boat but when I have had to winch off a yacht, it has been as a last resort (ie. survivor not wanting to jump into the water).
For my liking, yachts and helicopter winch ops don't mix.
I have only used the hi-line for
stretcher winches from vessels. Personnel recovery, I believe, is easier accomplished by paying out cable and the aircraft moving back away from the liferaft/dinghy so that the downwash doesn't hinder your down-the-wire man (and survivor). This gives the pilot reference on the target.
I suppose there are many ways to skin a cat!