A 6.1m fibreglass boat with three POB reported problems near the Radio Mast.  The motor was running but there was no drive.  Weather conditions were good with a 13-16kt wind from NNW and calm sea. An all stations call was transmitted and a good samaritan offered to assist and towed the boat back.  Both boats were safely back in port at 1450hr. Many thanks to the good samaritan for their assistance.