When his dad received the text he contacted the coastguards, giving his son's position.
It matched up with a position given in an emergency signal received by coastguards in Falmouth.
So a helicopter and lifeboat were scrambled to the scene - and everyone was rescued safely.
A coastguard spokesman said there had been several cases in the past of people in trouble at sea being saved by text message.
"We understand that texting can be sent to much longer distances than a voice call," he said.
But he added that the best way for stranded sailors to raise the alert was by VHF radio, if possible.
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