The missing man's boat was found running off Busselton last night.
Missing Australind man Ian Shardlow.
The search for a 76-year-old sailor missing off the Bussleton coast has been scaled back as hopes fade of finding him alive.
Ian Shardlow, a grandfather from Australind near Bunbury, is believed to have fallen overboard without a life jacket.
Mr Shardlow's six-metre catamaran, Two Up, was found floating off Busselton, about 230 kilometres south of Perth, on Thursday night after he was reported missing by his family when he didn't return from a day trip.
The yacht was found about four nautical miles offshore with its sails down and motor running with no one on board.
Police said the search had been scaled back to one aircraft and two vessels, which would continue to look for him.
AAP
Australind yachtsman missing off Busselton
His yacht was found drifting with the engine on, but no sign of the man on board.
He had sailed from Port Geographe just after lunch yesterday, but failed to return last night.
Volunteer marine rescue found the boat off Busselton around 8pm last night, four and a half nautical miles north of the marina.
Emergency services began an air and sea search last night, searching until 3am, and then began again this morning at first light.
Police believe the man has fallen overboard, but is wearing a life jacket.
Senior Constable Shane Larsen from Busselton Police said the emergency services are currently searching the area based on information supplied by the Water Police.
“We are undergoing grid searches from Cape Naturaliste right across the bay.
“The search area will change every hour as the tides and currents move.”