Three fishermen are missing after their boat capsized seven nautical miles off-shore from Hawston in the Western Cape on Friday.The National Sea Rescue Institute (NSRI) launched a search operation following reports from the families of the missing men, who were suspected to be lost at sea between Hawston and Kleinmond.According to NSRI spokesperson Craig Lambinon, a Skymed helicopter located the fishermen's boat, but without the crew."Despite an extensive search, no sign of the fishermen - believed to be aged in their 30s and 40s - has been found. Police and the Police dive unit are continuing in an ongoing search operation and investigations into the incident," Lambinon said in a statement."The casualty boat was towed to Hermanus harbour, recovered and handed to the family members of the missing fishermen."Telkom Maritime Radio services assisted with VHF marine radio communications and an all ships alert has been posted ... for any signs of the three missing fishermen."