From FindMyPast:
Name: Mrs M MAUCHAN
Date of departure: 2 October 1952
Port of departure: Southampton
Passenger destination port: Cape, South Africa
Passenger destination: Cape, South Africa
Date of Birth: 1901 (calculated from age)
Age: 51
Marital status:
Sex: Female
Occupation: H'wife
Name: Miss S MAUCHAN
Date of departure: 2 October 1952
Port of departure: Southampton
Passenger destination port: Cape, South Africa
Passenger destination: Cape, South Africa
Date of Birth: 1930 (calculated from age)
Age: 22
Marital status:
Sex: Female
Occupation: Typist
Ship: CARNARVON CASTLE
Official Number: 148766
Master's name: Capt Oakley
Steamship Line: Union Castle Line
Where bound: South Africa
Square feet:
Registered tonnage: 11.611
Passengers on voyage: 604
------------------------------------------------
Name: Mr A MAUCHAN
Date of departure: 9 September 1954
Port of departure: Southampton
Passenger destination port: Cape, South Africa
Passenger destination: Cape, South Africa
Date of Birth: 1915 (calculated from age)
Age: 39
Marital status:
Sex: Male
Occupation: Printer
Ship: PRETORIA CASTLE
Official Number: 181944
Master's name: Cap G Mayhew
Steamship Line: Union Castle Line
Where bound: South Africa
Square feet:
Registered tonnage: 17000
Passengers on voyage 701
----------------------------------------------------
Name: Mrs M MAUCHAN
Date of departure: 7 October 1954
Port of departure: Southampton
Passenger destination port: Cape, South Africa
Passenger destination: Cape, South Africa
Date of Birth: 1902 (calculated from age)
Age: 52
Marital status:
Sex: Female
Occupation: Manager
Ship: EDINBURGH CASTLE
Official Number: 57327
Master's name: Capt W Andrews
Steamship Line: Union Castle Line
Where bound: South Africa
Square feet:
Registered tonnage: 17000
Passengers on voyage 702
I am not sure that the family would have travelled to Vereeniging by boat as this town is very far from the nearest port although it is on the Vaal River. Flying boats did land on the Vaal Dam (just outside Vereeniging) between 1937 and 1950.
Regards
Moira