The man was sailing past the Demie de Pas beacon, off Jersey’s south coast, at about 1pm on Monday when the accident happened.
The alarm was raised by a fisherman who saw the boat heading towards rocks and phoned the emergency services.
The RNLI St Helier inshore lifeboat was sent out and the crew found the man semi-conscious and barely coherent.
In a statement, they said: ‘The yacht had already been rigged for a tow by the fishing boat and, in view of the casualty’s reluctance to be moved and the risks involved in moving him, the decision was taken to leave him on the yacht, administer casualty care and monitor his condition, and proceed into St Helier Harbour.
‘The three boats proceeded to the visitor moorings in St Helier Harbour where they were met by awaiting ambulance crew.’
