This date marked the formation of the South African Naval Service. With three ships, the Protea, Sonneblom and Immortelle and their crewsit formed the nucleus of a South African navy. Each ship had the prefix H.M.S.A.S. (His Majesty's South African Ship).   

There were several forerunners to this institution. The first  was  the Natal Naval Volunteers (N.N.V.), formed in 1885, which was in active service in both the Anglo-Boer War 2 (!899-1902) and the Zulu Rebellion (1906). The Cape Naval Volunteers corps was founded in 1905 in Cape Town and in 1913 the Royal Navy Volunteer Reserve, South African division, was formed and placed under control of the British Admiralty.

In 1948 the South African Navy was given its present title, but its history dated many years back. The SA Navy, together with the rest of the South African Defence Force (SADF), became part of the South African National Defence Force (SANDF) in 1994.

References:

1. Wallis, F. (2000). Nuusdagboek: feite en fratse oor 1000 jaar, Kaapstad: Human & Rousseau.
2. Potgieter, D.J. et al. (eds)(1970). Standard Encyclopaedia of Southern Africa, Cape Town: NASOU, v. 8, p. 113.
3. http://en.wikipedia.org/wiki/South_African_Navy
4. http://www.navy.mil.za/aboutus/history/ambassadors.htm