A 6m boat with 3 POB reported it had an engine problem and requested a tow.  The boat was 100m east of Whale Island. An all stations alert was transmitted and a good samaritan offered assistance. Sea conditions were good with 10kt wind from the east and calm seas. At 1056hr the good samaritan had the boat under tow and at 1203hr both boats were safely back in port. Many thanks to the good samaritan.