On the Tomnod website, people are asked to tag objects as either ship or boat, life raft or “other” in images.

Tomnod is run by commercial satellite company DigitalGlobe.

“The crowd sourcing theory operates on the belief that untrained observers who pick the same target can be as accurate as an expert.

“Anyone with access to a computer and the internet can join the online search party.”

On 12 February, Murray’s family reported to the maritime rescue co-ordination centre (MRCC) in Cape Town that the catamaran was overdue after it missed its expected arrival date 10 days before.

The yacht’s emergency position indicating radio beacon (EPIRB) had not been activated.

If a signal from the EPIRB is detected then search and rescue will be activated, the extent of which is dependent on resources available in the area at the time.

The Australian maritime safety authority issued an urgent broadcast to shipping about the missing yacht, which remains in place until the end of the month when it will be reviewed.

Skipper Murray, aged 58, has over 25 years’ experience at sea, including multiple international catamaran and yacht deliveries.

Robertson, aged 59, is also an experienced yachtsman and a member of the Royal Natal Yacht Club. Payne is 20 years old.