An off-duty policeman had been walking his dog on the beach when he spotted the board sailor in the water at approximately 4.30 pm.
"The officer alerted another member of the public who was watching scooter ducks through a telescope from the sea wall," Dave Miller, HM coastguard sector manager told the Observer afterwards.
"The police officer became concerned about the safety of the sailor as he was in the water and was not making any headway towards the shore, so he asked the gentleman to keep an eye on him through his telescope," he explained.
"The help of a third member of the public who was walking along the shore at the time and who had a mobile telephone was also sought."
They contacted Milford Haven coastguards who tasked the Tenby coastguard team and the inshore lifeboat to the scene.
The coastguard team guided the inshore crew to the man, who had got into difficulties after the fin on his board had broken, and he and his rig were recovered safe and well from the sea.
The sailor, who was aged 52 and from London, was then taken back to shore at Amroth.