I can vouch for the safety of winching to yachts, both large and small and under sail or power.
The routine is that a yacht is chosen randomly whilst airborne and the radio frequency displayed on a board
If they are willing, a thorough brief is passed and the exercise carried out. There are various safeguards to protect those on the yacht. E.g. Engine failure must not endanger the yacht, downwash must be just clear of the sail.
During the exercise a careful eye is kept on the yacht crews actions for obvious reasons.
It has been done for decades and it has come in very handy on numerous occasions and saved more than a few necks.
As most SAR guys and gals know, it is just another technique that may be appropriate in some circumstances and realistic training has to take place for the calls that the unit is likely to get.
Cheers
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