A father and son and two teenagers clung onto the upturned hull of their capsized boat for seven hours before they were rescued by the NSRI in the Western Cape.
The four, from three families visiting the Hermanus area for a weekend break, had gone fishing in a small cabin ski-boat on Saturday.
They launched in calm seas at Hawston. It is believed a small wave had peaked unexpectedly and gently capsized their boat without warning, at about 5.30am, throwing them into the water.
They were about 100 metres offshore with no means to raise the alarm.
Jean le Roux, NSRI Hermanus duty coxswain, said their crew was activated at lunchtime after anglers alerted them.
The father, 49, his 17-year-old son, from Somerset West, and two 14-year-old boys from Stellenbosch, were treated for hypothermia.
The son was also treated for a head wound.
They are all recovering in hospital and they are expected to make full recoveries, the NSRI said.
**TimesLIVE**