I tend to apply a simple rule of thumb.
If you feel the need to use the AHT for real, I would not use it for
live winching unless its a wet lift or into something that the winchman will bounce off (liferaft/rib etc).
If you are struggling to winch to a larger vessel (such as a short yacht with a tall mast), the AHT can be used to allow the winchop to place a hi-line onto the deck, the caveat being that the hover height is above that of the highest obstruction. That way, if it goes pear shaped, no harm done, just get another hi-line.
Once the hi-line is on deck, the pilot should be able to fly the hover using the available references as the aircraft will be offset a few units, with the SOP being that he stops movement towards the vessel when he is approaching the limit of his visual references. The winchman can then be lowered/recovered using the hi-line to create the appropriate angle on the cable.
As suggested by the previous posters, success as always comes from practice.
