California coastguards are searching for Microsoft researcher Jim Gray, who was reported missing at 8.30pm on Sunday after failing to return from a solo boat trip.
An experienced yachtsman, Gray sailed early Sunday from a marina near Fort Mason in San Francisco, The San Jose Mercury News reports. He had told family he planned to scatter his mother's ashes on the Farallon Islands, 27 miles west of the Golden Gate Bridge. He called home at 10.30am, saying he would soon be passing out of cell phone range.
Coastguards were alerted when he did not make a promised call when back in range, and a dispatched a spotter to search a 4,000 square mile area.
Coastguard Lieutenant Amy Marrs said: "There has been no sightings of Jim Gray or the vessel. Based on his experience and the reports of the good condition of his boat, we have no clues." The sailing conditions around San Francisco were reportedly good.
Gray, 63, founded and managed Microsoft's Bay Area Research Centre. In 1998 he bagged the Turing Prize for his work on databases and transaction processing. Microsoft spokesman Doug Free said: "Our thoughts are with Jim and his family as we hope for his safe return."